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1.
Reprod Domest Anim ; 58(3): 405-413, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36448722

ABSTRACT

The present study was conducted to determine the effects of dietary chitosan supplementation on sexual behaviour responses, testicular development, and semen quality traits of New Zealand White (NZW) rabbit bucks. Twenty-four 5-week-old rabbit bucks were used in this experiment. Animals were grouped into four equal experimental groups: the control group was fed only on a basal diet, whereas the other groups were fed the basal diet supplemented with three levels of chitosan at 0.2, 0.4, or 0.6 g/kg, respectively. Also, bucks that received chitosan at 0.2 and 0.4 g/kg had a significantly earlier time of sexual libido (p ≤ .05) and had significantly higher ejaculate volume and sperm concentration than other groups (p ≤ .001). Furthermore, basic and sexual behaviours were significantly improved in bucks fed chitosan at 0.2 and 0.4 g/kg compared with other groups. Therefore, it could be concluded that using chitosan at 0.2 and 0.4 g/kg enhanced sexual behaviour, improved semen quality, and reproductive efficiency in the NZW rabbit bucks.


Subject(s)
Chitosan , Semen Analysis , Rabbits , Male , Animals , Semen Analysis/veterinary , Chitosan/pharmacology , Spermatozoa/physiology , Semen/physiology , Diet , Dietary Supplements , Goats/physiology
2.
Reprod Domest Anim ; 58(2): 191-206, 2023 Feb.
Article in English | MEDLINE | ID: mdl-36337040

ABSTRACT

Quercetin is one of the most used antioxidant flavonoids and largely exists in many fruits and vegetables because of its capability to scavenge the free reactive oxygen species (ROSs) by repressing lipid peroxy radical fusion, metal ion chelating through enzyme inhibition, and adopting the repair mechanisms. It also exhibits various biological actions, including antioxidative, anti-inflammatory and antimicrobial activities. Furthermore, it contributes well to sustaining the endogenous cellular antioxidant defence system. The process of cryopreservation is associated with increased oxidative stress, and some steps are potential sources of ROSs, including the method of semen collection, handling, cryopreservation culture media, and thawing, which result in impaired sperm function. Several antioxidants have been proposed to counteract the harmful impact of ROS during semen cryopreservation. The antioxidant capability of quercetin has been verified in different animal species for providing valuable defence to sperm during the cryopreservation process. The beneficial properties of quercetin on various parameters of fresh and post-thaw sperm in different species are clarified in this review. More in-depth investigations are required to clarify quercetin's mechanism of action in different animal species.


Subject(s)
Quercetin , Semen Preservation , Male , Animals , Quercetin/pharmacology , Antioxidants/pharmacology , Semen , Animals, Domestic , Sperm Motility , Cryoprotective Agents/pharmacology , Spermatozoa , Cryopreservation/veterinary , Semen Analysis/veterinary , Semen Preservation/veterinary
3.
Front Vet Sci ; 9: 899570, 2022.
Article in English | MEDLINE | ID: mdl-35812871

ABSTRACT

Decreasing male fertility encouraged the investigators to innovate accurate diagnostic non-invasive methods for detection of changes in the testicular parenchyma. Ultrasonography (US) has the potential to be used in this manner for decades, but magnetic resonance imaging (MRI) is still of limited application in animals for this purpose. The current study was designed to describe appearances and quantitative MRI attributes of the normal testes, epididymis besides angiography of testicular artery in camels. About 30 apparently healthy male dromedary camels aged 8-14 years were slaughtered during the rutting season. Immediately after slaughtering, the male gonads (n = 30 pairs of testicles and epididymis) were subjected to morphometric evaluation using a Vernier caliper and ultrasound scanning. Epididymial sperms were evaluated for motility, vitality and abnormality. MRI was performed for testes (n=16) by using a 1.5T Excite-II MRI apparatus of Sigma. Radiography and angioarchitecture of testicular artery (n=24) were done. Camel testicular length, width, and depth showed non-significant differences between a Vernier caliper or sonar. The MRI results revealed that both the testis and epididymis have homogenously intermediate signal (T1) and testes have hyperintense signal, with slightly lower signal in the epididymis (T2). In conclusion, both the ultrasonography and MRI techniques, with each respective computer-assisted imaging, could be used to detect the histomorphological changes of the camels' testicles. However, US imaging remains the first diagnostic technique for evaluating the reproductive health in men for its lower cost and accuracy. MRI is beneficial when the sonograms are inconclusive and/or equivocal. It shows the examined tissues in greater anatomical details compared to ultrasonography. Further studies are needed to compare between characteristics of US and MRI of normal testes and epididymis with testicular artery angiography in living camel during rut season and non-rut season and between normal healthy and affected diseased genitalia.

4.
Front Vet Sci ; 9: 899434, 2022.
Article in English | MEDLINE | ID: mdl-35812886

ABSTRACT

This study aimed to investigate the effect of oral supplementation of rumen-protected L-arginine on semen quality, testes, and accessory genital glands biometry in rams. Ten apparently healthy and fertile rams were randomly divided into two equal groups; control, and rumen-protected L-arginine (20 mg/Kg body weight for 30 days) treated group. In all rams, ultrasonographic measurements of the testes and the accessory genital glands and blood sampling were performed at day (D)10, D20, and D30 (D0 is the start of supplementation). Semen ejaculates were collected twice/week and semen quantity, and quality was examined. Our results showed that, in the L-arginine treated group, there were significant increase in the ultrasound biometric measurement of right seminal vesicle (RSV) and right Cowper's gland (RCG) at D10, both testes, tail of the epididymis (TE), SV, and CG of both sides at D20, and of both testes, RTE, RSV, RCG, and LSV at D30. Semen quality and quantity parameters were significantly improved in L-arginine treated group. Moreover, testosterone level in the L-arginine treated group was significantly higher than that in the Control group. Serum thyroxine and glutathione peroxidase concentrations were significantly higher in the L-arginine treated group. The present study concluded that oral supplementation with rumen-protected L-arginine is beneficial in improvement of rams' fertility.

5.
Reprod Domest Anim ; 57(10): 1101-1112, 2022 Oct.
Article in English | MEDLINE | ID: mdl-35754099

ABSTRACT

The reproductive consequences of global warming representing heat stress (HS) have been widely received more attention in the last decades. HS induced significant influence on the male reproductive cell, especially sperm functionally. Reduction in the sperm function induced by HS leads to failure of fertility potential. The main effects of HS on sperm are reducing sperm motility, increased abnormalities and changes in the fluidity of the membrane as well as cell morphology. Moreover, the destruction of mitochondrial function could be the result of adverse influences of HS. The protein contents and enzymes of mitochondria were lowered after the exposure of sperm to HS. Some natural antioxidants were used for improving sperm mitochondrial function under HS conditions. In this review, it was highlighted the potential influences of HS on sperm function through reduction in ATP Synthesis yield, mitochondrial activity, mitochondrial protein contents and mitochondrial enzymes, which involves the interference of mitochondrial remodelling in sperm of animals.


Subject(s)
Antioxidants , Heat Stress Disorders , Adenosine Triphosphate/metabolism , Animals , Antioxidants/metabolism , Antioxidants/pharmacology , Heat Stress Disorders/metabolism , Heat Stress Disorders/veterinary , Male , Mitochondria/physiology , Mitochondrial Proteins/metabolism , Mitochondrial Proteins/pharmacology , Semen/metabolism , Sperm Motility , Spermatozoa/physiology
6.
J Adv Res ; 38: 119-129, 2022 05.
Article in English | MEDLINE | ID: mdl-35572411

ABSTRACT

Introduction: Although the synthetic vitamin D analogue, Paricalcitol, and omega-3 Fatty acids (ω-3) alleviated diabetic nephropathy (DN), their combination was not previously explored. Objectives: This study measured the potential ameliorative effects of single and dual therapies of Paricalcitol and/or ω-3 against DN. Methods: Forty rats were assigned as follow: negative (NC) and positive (PC) controls, Paricalcitol, ω-3 and Paricalcitol + ω-3 groups. Diabetes was generated by high-fat/high-fructose diet and a single streptozotocin injection (40 mg/kg). DN was confirmed by raised fasting blood glucose (FBG), polyuria, proteinuria, and decreased urine creatinine levels. Paricalcitol intraperitoneal injections (0.25 µg/Kg/day; 5 times/week) and oral ω-3 (415 mg/kg/day; 5 times/week) started at week-9 and for eight weeks. Results: The PC group showed hyperglycaemia, dyslipidaemia, abnormal renal biochemical parameters, elevated caspase-3 expression, and increased apoptosis by TUNEL technique. The mRNAs and proteins of the pathogenic molecules (TGF-ß1/iNOS) and markers of tissue damage (NGAL/KIM-1) augmented substantially in the PC renal tissues relative to the NC group. The oxidative stress (MDA/H2O2/protein carbonyl groups) and pro-inflammatory (IL1ß/IL6/TNF-α) markers increased, whereas the anti-inflammatory (IL10) and anti-oxidative (GSH/GPx1/GR/SOD1/CAT) declined, in the PC renal tissues. The monotherapy groups were associated with ameliorated FBG, lipid profile and renal functions, and diminished TGF-ß1/iNOS/NGAL/KIM-1/Caspase-3 alongside the apoptotic index than the PC group. The oxidative stress and pro-inflammatory markers decreased, whilst the anti-oxidative and anti-inflammatory molecules escalated, in the monotherapy groups than the PC group. Although the Paricalcitol renoprotective actions were better than ω-3, all the biomarkers were abnormal than the NC group. Alternatively, the Paricalcitol + ω-3 protocol exhibited the best improvements in metabolic control, renal functions, oxidative stress, inflammation, and apoptosis. However, FBG and tissue damage were persistently higher in the co-therapy group than controls. Conclusions: Both monotherapies showed modest efficacy against DN, whereas their combination displayed boosted renoprotection, possibly by enhancing renal anti-oxidant and anti-inflammatory pathways.


Subject(s)
Diabetes Mellitus , Diabetic Nephropathies , Fatty Acids, Omega-3 , Animals , Anti-Inflammatory Agents/pharmacology , Anti-Inflammatory Agents/therapeutic use , Caspase 3/metabolism , Diabetic Nephropathies/drug therapy , Diabetic Nephropathies/metabolism , Diabetic Nephropathies/pathology , Ergocalciferols , Fatty Acids, Omega-3/pharmacology , Fatty Acids, Omega-3/therapeutic use , Female , Humans , Hydrogen Peroxide/metabolism , Lipocalin-2/therapeutic use , Male , Rats , Transforming Growth Factor beta1/metabolism , Transforming Growth Factor beta1/therapeutic use
7.
Front Cell Dev Biol ; 8: 616762, 2020.
Article in English | MEDLINE | ID: mdl-33505968

ABSTRACT

The rho-associated coiled-coil-containing proteins (ROCKs or rho kinase) are effectors of the small rho-GTPase rhoA, which acts as a signaling molecule to regulate a variety of cellular processes, including cell proliferation, adhesion, polarity, cytokinesis, and survival. Owing to the multifunctionality of these kinases, an increasing number of studies focus on understanding the pleiotropic effects of the ROCK signaling pathway in the coordination and control of growth (proliferation, initiation, and progression), development (morphology and differentiation), and survival in many cell types. There is growing evidence that ROCKs actively phosphorylate several actin-binding proteins and intermediate filament proteins during oocyte cytokinesis, the preimplantation embryos as well as the stem cell development and differentiation. In this review, we focus on the participation of ROCK proteins in oocyte maturation, blastocyst formation, and stem cell development with a special focus on the selective targeting of ROCK isoforms, ROCK1, and ROCK2. The selective switching of cell fate through ROCK inhibition would provide a novel paradigm for in vitro oocyte maturation, experimental embryology, and clinical applications.

8.
3 Biotech ; 7(5): 351, 2017 Oct.
Article in English | MEDLINE | ID: mdl-28955648

ABSTRACT

Growth of Fusarium sp. BVKT R2, a potential isolate of forest soils of Eastern Ghats on birchwood xylan in mineral salts medium (MSM) under un-optimized conditions of 30 °C, pH of 5.0, 150 rpm and inoculum size of 5 agar plugs for 7 days, yielded titer of 1290 U/mL of xylanase (EC 3.2.1.8). The effect of various operating parameters such as different substrates and their concentration, additional carbon and nitrogen sources, incubation temperature, initial pH, agitation and inoculum size on the production of xylanase by Fusarium sp. BVKT R2 was studied in shake flask culture by one factor at a time approach. The same culture exhibited higher production of xylanase (4200 U/mL) when grown on birch wood xylan in MSM under optimized conditions with an additional carbon source-sorbitol (1.5%) nitrogen source-yeast extract (1.5%) temperature of 30 °C, pH of 5.0, agitation of 200 rpm and inoculum of 6 agar plugs for only 5 days. There was enhancement in xylanase production under optimized conditions by 3.2 folds over yields under un-optimized conditions. Growth of BVKT R2 culture on locally available lignocelluloses-sawdust, rice straw and cotton stalk-in MSM for 5 days released soluble sugars to the maximum extent of 52.76% with respect to sawdust indicating its greater importance in saccharification essential for biotechnological applications.

9.
Front Plant Sci ; 8: 1934, 2017.
Article in English | MEDLINE | ID: mdl-29552020

ABSTRACT

Pearl millet is a climate resilient crop and one of the most widely grown millets worldwide. Heterotic hybrid development is one of the principal breeding objectives in pearl millet. In a maiden attempt to identify heterotic groups for grain yield, a total of 343 hybrid parental [maintainer (B-) and restorer (R-)] lines were genotyped with 88 polymorphic SSR markers. The SSRs generated a total of 532 alleles with a mean value of 6.05 alleles per locus, mean gene diversity of 0.55, and an average PIC of 0.50. Out of 532 alleles, 443 (83.27%) alleles were contributed by B-lines with a mean of 5.03 alleles per locus. R-lines contributed 476 alleles (89.47%) with a mean of 5.41, while 441 (82.89%) alleles were shared commonly between B- and R-lines. The gene diversity was higher among R-lines (0.55) compared to B-lines (0.49). The unweighted neighbor-joining tree based on simple matching dissimilarity matrix obtained from SSR data clearly differentiated B- lines into 10 sub-clusters (B1 through B10), and R- lines into 11 sub-clusters (R1 through R11). A total of 99 hybrids (generated by crossing representative 9 B- and 11 R- lines) along with checks were evaluated in the hybrid trial. The 20 parents were evaluated in the line trial. Both the trials were evaluated in three environments. Based on per se performance, high sca effects and standard heterosis, F1s generated from crosses between representatives of groups B10R5, B3R5, B3R6, B4UD, B5R11, B2R4, and B9R9 had high specific combining ability for grain yield compared to rest of the crosses. These groups may represent putative heterotic gene pools in pearl millet.

10.
MedEdPublish (2016) ; 6: 196, 2017.
Article in English | MEDLINE | ID: mdl-38406410

ABSTRACT

This article was migrated. The article was marked as recommended. Purpose: This study explored comics as a tool for teaching medical and physician assistant (PA) students about end-of-life decisions and advance care planning. Methods: Using a mixed method convergent design, a survey (consisting of a five-point Likert scale and open-ended questions) was administered to second-year medical and first-year PA students enrolled in an Ethics and Professionalism class at a US medical school. The survey assessed students' perspectives on the addition of a comic "Betty P." to assigned readings and about the use of comics in the classroom. Quantitative results were compared by demographics, and open-ended responses were analyzed qualitatively for emergent themes. Quantitative and qualitative findings were compared for correspondence. Results: Of the 145 students who completed the survey (83%), 141 students (81%) had read the comic. The vast majority (89%) felt that "Betty P." helped them understand end of life care for patients, and 84% felt that the comic did not distract them from the seriousness of the subject. Qualitative analysis revealed 2 major themes: 1) comics were educational, and 2) comics engaged learners emotionally. We observed convergence between quantitative and qualitative results. Conclusion: Integrating comics as a supplemental teaching tool is an innovative way to engage medical students.

11.
Toxicol Appl Pharmacol ; 308: 20-31, 2016 10 01.
Article in English | MEDLINE | ID: mdl-27521977

ABSTRACT

Chlorpyrifos (CPF) and CPF-oxon (CPO) are known to inhibit neurite outgrowth but little is known about their ability to induce neurite retraction in differentiating neuronal cells. The aims of this study were to determine the ability of these compounds to destabilize neurites and to identify the key molecular events involved. N2a cells were induced to differentiate for 20h before exposure to CPF or CPO for 2-8h. Fixed cell monolayers labeled with carboxyfluorescein succinimidyl ester or immunofluorescently stained with antibodies to tubulin (B512) or phosphorylated neurofilament heavy chain (Ta51) showed time- and concentration-dependent reductions in numbers and length of axon-like processes compared to the control, respectively, retraction of neurites being observed within 2h of exposure by live cell imaging. Neurofilament disruption was also observed in treated cells stained by indirect immunofluorescence with anti-phosphorylated neurofilament heavy chain (NFH) monoclonal antibody SMI34, while the microtubule network was unaffected. Western blotting analysis revealed transiently increased levels of reactivity of Ta51 after 2h exposure and reduced levels of reactivity of the same antibody following 8h treatment with both compounds, whereas reactivity with antibodies to anti-total NFH or anti-tubulin was not affected. The alteration in NFH phosphorylation at 2h exposure was associated with increased activation of extracellular signal-regulated protein kinase ERK 1/2. However, increased levels of phosphatase activity were observed following 8h exposure. These findings suggest for the first time that organophosphorothionate pesticide-induced neurite retraction in N2a cells is associated with transient increases in NFH phosphorylation and ERK1/2 activation.


Subject(s)
Chlorpyrifos/toxicity , Insecticides/toxicity , MAP Kinase Signaling System , Neurites/drug effects , Neurofilament Proteins/metabolism , Animals , Cell Differentiation , Cell Line, Tumor , Mice , Phosphorylation
12.
Nanoscale ; 8(22): 11392-7, 2016 Jun 02.
Article in English | MEDLINE | ID: mdl-27211810

ABSTRACT

Herein, we have examined distinctive structural and functional variations of cellular components during apoptotic cell death induced by a targeted theranostic nanoprobe, MMP-SQ@GNR@LAH-DOX, which acted as a SERS "on/off" probe in the presence of a MMP protease and executed synergistic photothermal chemotherapy, as reflected by the SERS fingerprinting, corresponding to the phosphodiester backbone of DNA.

13.
PLoS One ; 10(11): e0141330, 2015.
Article in English | MEDLINE | ID: mdl-26555695

ABSTRACT

Interleukin-6 (IL-6) is an important member of the cytokine superfamily, exerting pleiotropic actions on many physiological processes. Over-production of IL-6 is a hallmark of immune-mediated inflammatory diseases such as Castleman's Disease (CD) and rheumatoid arthritis (RA). Antagonism of the interleukin IL-6/IL-6 receptor (IL-6R)/gp130 signaling complex continues to show promise as a therapeutic target. Monoclonal antibodies (mAbs) directed against components of this complex have been approved as therapeutics for both CD and RA. To potentially provide an additional modality to antagonize IL-6 induced pathophysiology, a peptide-based antagonist approach was undertaken. Using a combination of molecular design, phage-display, and medicinal chemistry, disulfide-rich peptides (DRPs) directed against IL-6 were developed with low nanomolar potency in inhibiting IL-6-induced pSTAT3 in U937 monocytic cells. Targeted PEGylation of IL-6 binding peptides resulted in molecules that retained their potency against IL-6 and had a prolongation of their pharmacokinetic (PK) profiles in rodents and monkeys. One such peptide, PN-2921, contained a 40 kDa polyethylene glycol (PEG) moiety and inhibited IL-6-induced pSTAT3 in U937 cells with sub-nM potency and possessed 23, 36, and 59 h PK half-life values in mice, rats, and cynomolgus monkeys, respectively. Parenteral administration of PN-2921 to mice and cynomolgus monkeys potently inhibited IL-6-induced biomarker responses, with significant reductions in the acute inflammatory phase proteins, serum amyloid A (SAA) and C-reactive protein (CRP). This potent, PEGylated IL-6 binding peptide offers a new approach to antagonize IL-6-induced signaling and associated pathophysiology.


Subject(s)
Interleukin-6/antagonists & inhibitors , Peptides/pharmacology , Amino Acid Sequence , Animals , Drug Design , Half-Life , Humans , Hybridomas , Interleukin-6/chemistry , Interleukin-6/metabolism , Macaca fascicularis , Male , Mice , Mice, Inbred BALB C , Mice, Inbred ICR , Models, Molecular , Molecular Sequence Data , Peptide Library , Peptides/chemistry , Peptides/metabolism , Protein Conformation , Random Allocation , Rats , Rats, Sprague-Dawley , Receptors, Interleukin-6/chemistry , Recombinant Proteins/pharmacology , STAT3 Transcription Factor/metabolism , Structure-Activity Relationship , U937 Cells
14.
J Proteome Res ; 14(5): 2255-66, 2015 May 01.
Article in English | MEDLINE | ID: mdl-25760677

ABSTRACT

We describe PGTools, an open source software suite for analysis and visualization of proteogenomic data. PGTools comprises applications, libraries, customized databases, and visualization tools for analysis of mass-spectrometry data using combined proteomic and genomic backgrounds. A single command is sufficient to search databases, calculate false discovery rates, group and annotate proteins, generate peptide databases from RNA-Seq transcripts, identify altered proteins associated with cancer, and visualize genome scale peptide data sets using sophisticated visualization tools. We experimentally confirm a subset of proteogenomic peptides in human PANC-1 cells and demonstrate the utility of PGTools using a colorectal cancer data set that led to the identification of 203 novel protein coding regions missed by conventional proteomic approaches. PGTools should be equally useful for individual proteogenomic investigations as well as international initiatives such as chromosome-centric Human Proteome Project (C-HPP). PGTools is available at http://qcmg.org/bioinformatics/PGTools.


Subject(s)
Chromosomes, Human/chemistry , Colorectal Neoplasms/genetics , Pancreatic Neoplasms/genetics , Proteomics/statistics & numerical data , Software , Cell Line, Tumor , Databases, Protein , Humans , Mass Spectrometry , Molecular Sequence Annotation , Open Reading Frames , Proteome/genetics , Proteomics/methods , Sequence Analysis, RNA , Transcriptome
15.
Dev Cell ; 31(4): 405-19, 2014 Nov 24.
Article in English | MEDLINE | ID: mdl-25453557

ABSTRACT

Caveolae are cell-surface membrane invaginations that play critical roles in cellular processes including signaling and membrane homeostasis. The cavin proteins, in cooperation with caveolins, are essential for caveola formation. Here we show that a minimal N-terminal domain of the cavins, termed HR1, is required and sufficient for their homo- and hetero-oligomerization. Crystal structures of the mouse cavin1 and zebrafish cavin4a HR1 domains reveal highly conserved trimeric coiled-coil architectures, with intersubunit interactions that determine the specificity of cavin-cavin interactions. The HR1 domain contains a basic surface patch that interacts with polyphosphoinositides and coordinates with additional membrane-binding sites within the cavin C terminus to facilitate membrane association and remodeling. Electron microscopy of purified cavins reveals the existence of large assemblies, composed of a repeating rod-like structural element, and we propose that these structures polymerize through membrane-coupled interactions to form the unique striations observed on the surface of caveolae in vivo.


Subject(s)
Caveolae/chemistry , Caveolae/metabolism , Caveolins/chemistry , Caveolins/metabolism , Cytoplasm/metabolism , RNA-Binding Proteins/chemistry , RNA-Binding Proteins/metabolism , Amino Acid Sequence , Animals , Caveolae/ultrastructure , Crystallography, X-Ray , Cytoplasm/chemistry , Cytoplasm/ultrastructure , Membrane Proteins/metabolism , Microscopy, Electron , Molecular Sequence Data , Protein Structure, Quaternary , Signal Transduction/physiology , Zebrafish/metabolism
17.
Dalton Trans ; 43(28): 10940-6, 2014 Jul 28.
Article in English | MEDLINE | ID: mdl-24903008

ABSTRACT

Herein, we have developed a series of isostructural mixed Ln(3+)-4-(dipyridin-2-yl)aminobenzoate coordination polymers [Ln(3+) = Eu(3+) (1), Tb(3+) (2), and Gd(3+) (3)], and characterized and investigated their photophysical properties. The results demonstrated that by gently tuning the excitation wavelength of these mixed lanthanide complexes, white light emission can be realized with the Commission Internationale de I'Eclairage coordinates (0.32, 0.34). Furthermore, by changing the concentration profiles of lanthanide ions stoichiometrically in mixed-lanthanide complexes and exciting at particular wavelengths, various emission colours can also be successfully obtained. The antenna ligand, 4-(dipyridin-2-yl)aminobenzoic acid, provides an efficient energy transfer for the sensitization of Eu(3+) and Tb(3+) complexes and exhibits red and green emissions, respectively. Most importantly, due to the high energy (32,150 cm(-1)) of the Gd(3+) ion lowest-lying emission level, the corresponding Gd(3+) complex displays ligand-centered visible emission in the blue light region, and hence it acts as a blue emitter. Therefore, Eu(3+) and Tb(3+) complexes in conjunction with a Gd(3+) complex is a suitable choice to obtain tunable white-light-emission from Ln(3+) coordination polymers. The morphological analyses of the mixed lanthanide coordination polymers by transmission electron microscopy (TEM) disclose that these compounds exist as unique crystalline nano-rods with an average diameter of 200 nm. The developed mixed lanthanide complexes also exhibit high thermal stability (~420 °C).

19.
Inorg Chem ; 51(16): 8818-26, 2012 Aug 20.
Article in English | MEDLINE | ID: mdl-22862678

ABSTRACT

Herein, a new aromatic carboxylate ligand, namely, 4-(dipyridin-2-yl)aminobenzoic acid (HL), has been designed and employed for the construction of a series of lanthanide complexes (Eu(3+) = 1, Tb(3+) = 2, and Gd(3+) = 3). Complexes of 1 and 2 were structurally authenticated by single-crystal X-ray diffraction and were found to exist as infinite 1D coordination polymers with the general formulas {[Eu(L)(3)(H(2)O)(2)]}(n) (1) and {[Tb(L)(3)(H(2)O)].(H(2)O)}(n) (2). Both compounds crystallize in monoclinic space group C2/c. The photophysical properties demonstrated that the developed 4-(dipyridin-2-yl)aminobenzoate ligand is well suited for the sensitization of Tb(3+) emission (Φ(overall) = 64%) thanks to the favorable position of the triplet state ((3)ππ*) of the ligand [the energy difference between the triplet state of the ligand and the excited state of Tb(3+) (ΔE) = (3)ππ* - (5)D(4) = 3197 cm(-1)], as investigated in the Gd(3+) complex. On the other hand, the corresponding Eu(3+) complex shows weak luminescence efficiency (Φ(overall) = 7%) due to poor matching of the triplet state of the ligand with that of the emissive excited states of the metal ion (ΔE = (3)ππ* - (5)D(0) = 6447 cm(-1)). Furthermore, in the present work, a mixed lanthanide system featuring Eu(3+) and Tb(3+) ions with the general formula {[Eu(0.5)Tb(0.5)(L)(3)(H(2)O)(2)]}(n) (4) was also synthesized, and the luminescent properties were evaluated and compared with those of the analogous single-lanthanide-ion systems (1 and 2). The lifetime measurements for 4 strongly support the premise that efficient energy transfer occurs between Tb(3+) and Eu(3+) in a mixed lanthanide system (η = 86%).

20.
Biochemistry ; 49(25): 5278-89, 2010 Jun 29.
Article in English | MEDLINE | ID: mdl-20507120

ABSTRACT

A striking feature of the CLIC (chloride intracellular channel) protein family is the ability of its members to convert between a soluble state and an integral membrane channel form. Direct evidence of the structural transition required for the CLIC protein to autonomously insert into the membrane is lacking, largely because of the challenge of probing the conformation of the membrane-bound protein. However, insights into the CLIC transmembrane form can be gained by biophysical methods such as fluorescence resonance energy transfer (FRET) spectroscopy. This approach was used to measure distances from tryptophan 35, located within the CLIC1 putative N-domain transmembrane region, to three native cysteine residues within the C-terminal domain. These distances were computed both in aqueous solution and upon the addition of membrane vesicles. The FRET distances were used as constraints for modeling of a structure for the CLIC1 integral membrane form. The data are suggestive of a large conformational unfolding occurring between the N- and C-domains of CLIC1 upon interaction with the membrane. Consistent with previous findings, the N-terminal domain of CLIC1 is likely to insert into the lipid bilayer, while the C-domain remains in solution on the extravesicular side of the membrane.


Subject(s)
Chloride Channels/metabolism , Membrane Proteins/metabolism , Chloride Channels/chemistry , Electron Spin Resonance Spectroscopy , Fluorescence Resonance Energy Transfer , Fluorescent Dyes , Humans , Models, Molecular , Protein Binding , Spectrometry, Fluorescence , Spin Labels
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