The effects of ultraviolet light on the biological and physical chemical properties of deoxyribonucleic acids

Ellagic acid-loaded soy protein isolate self-assembled particles: Characterization, stability, and antioxidant activity

The limited water solubility and bioactivity of lipophilic phytochemicals may be enhanced by delivery systems. Ellagic acid (EA) has antioxidant and anti-inflammatory properties, but low solubility and instability limit its use in the food industry. In this study, the pH-shift method was applied to encapsulate EA with soy protein isolate (SPI). The interaction, encapsulation, and protective potential of the EA-loaded soy SPI complexes (SPI-EA) were investigated. The fluorescence spectra results suggest that the reaction between SPI and EA is spontaneous, with hydrophobic interactions predominating. Binding of EA molecules quenches the intrinsic fluorescence of SPI, mainly static quenching, with a binding site involved in the binding process. The ultraviolet (UV)-visible spectroscopy of the SPI-EA complexes included the characteristic absorption peaks of both SPI and EA, and the scanning electron microscopy images further indicated that the EA had been successfully embedded in SPI. Fourier transform infrared spectroscopy illustrates that EA has significantly changed the secondary structure of the SPI, primarily in the form of a decreased content of α-helix structures and an increased content of β-sheet and random coil structures. The encapsulation efficiency of EA was concentration-dependent, up to 81.08%. The addition of EA reduces the size of SPI particles (d < 155 nm). In addition, the SPI-EA complex showed up to 81.05% and 96.46% 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity. TGA showed that the degradation temperature of SPI-EA complex could be extended up to 300°C. And by encapsulation of EA, the loss of EA under the action of UV light, heat treatment, and high concentration of salt ion sensitive environment can be reduced. PRACTICAL APPLICATION: Ellagic acid (EA), a natural bioactive with low water solubility and stability, can be enhanced by forming an inclusion complex with soy protein isolate (SPI). SPI-EA complex has broad potential applications in the food, beverage, and pharmaceutical industries. Multiple spectral analyses have contributed to our understanding of the formation and interaction mechanisms of the SPI-EA complex under pH-driven conditions. Stability assays have also aided in the development of dietary resources for EA.

Synthesis, characterization, cytotoxicity and DNA/BSA binding of two amino acid palladium(II) complexes derived from alanine and valine

Two novel palladium(II)-amino acid complexes, [Pd(Ala)2]·H2O (PA) and [Pd(Val)2].H2O (PV) (Ala = alanine; Val = valine) were synthesized and characterized through FTIR, UV/Vis, 1H-NMR spectroscopies, CHN analysis, X-ray crystallography and molar conductivity measurement. Furthermore, cytotoxicity of Pd(II) complexes against human leukemia cancer cell line, MOLT4 showed promising cancer cell death (CC50 = 0.71 ± 0.046 µM for PA; CC50 = 0.85 ± 0.063 µM for PV) that were less than cisplatin (1.59 ± 0.25 µM). Moreover, the interaction of both the complexes with DNA and BSA was studied using UV-Vis absorption and emission spectroscopic techniques that demonstrated the bindings occurred via van der Waals forces and hydrogen bond. Furthermore, the fluorescence titration showed that static quenching mechanism plays predominate role in binding process. All results showed that both complexes have more binding tendency to DNA in compared to BSA that can be a significant achievement for further medical purposes as a potential antitumor candidate. Finally, molecular docking simulation was performed for PA and PV complexes with DNA and BSA and demonstrated both complexes bind to the groove of DNA mainly by hydrogen bond and interact with site I of BSA via hydrogen bond as well.

Conceptual bases in restoration of scientific vertebrate collections

The scientific heritage preserved in Brazilian biological collections has inestimable value. Despite the research on curation and restoration of biological material is regarded as strategic, there is a lack of expertise in these areas in the country. These deficiencies often determine the use of obsolete or even inadequate procedures aimed at the recovery of material for research or exhibition, resulting in risk to valuable specimens. In the present work we provide a review of the literature on the restoration of biological specimens and summarize concepts employed in the restoration of mammals and birds of the Museu Nacional, Universidade Federal do Rio de Janeiro, exhibition in 2011. The aim of this work is to contribute to the development of protocols when interventions are needed to restore damaged specimens.

My life with adeno-associated virus: a long time spent studying a short genome

My 45 years of studying the molecular biology of adeno-associated virus are recounted. Additional activities as a mentor, department chair, and medical school administrator are described, as are my activities in the public sphere, which involved national issues related to science policy and medical education.

Can .OH scavengers protect against direct UV-C damage in vivo?

It has previously been shown that ethanol and tert-butanol protect poly(U) against strand breaks from pulsed laser ultraviolet (UV) photons (lambda = 248 nm). This protection is believed to be based on a modification of direct DNA damage, not on scavenging hydroxyl radicals. In this paper, several .OH scavengers were tested in vivo with Escherichia coli DNA repair-deficient mutants to see if protection could also be demonstrated with non-laser UV photons (lambda approximately 254 nm). No protection was observed.

Two-quantum UV photochemistry of nucleic acids: comparison with conventional low-intensity UV photochemistry and radiation chemistry

The action of high-intensity laser u.v. radiation on nucleic acid molecules and their constituents in vitro and in vivo is compared with the results of low-intensity u.v. photolysis and gamma-radiolysis.

Structural changes of ultraviolet-irradiated DNA derived from hydrodynamic measurements

The paper reports on sedimentation and viscosity measurements performed on ultraviolet-irradiated DNA from T7 phage and calf thymus. From the hydrodynamic data the relative changes in the mean molecular weight, radius of gyration, and effective Kuhn statistical segment length were calculated. The results show that ultraviolet irradiation (254 nm) leads to a significant decrease of the effective statistical segment length of DNA which may be due to small local helix kinks (produced by the generation of photodimers) and a local increase of chain flexibility. Alterations in the overall DNA conformation may be observed even at low fluences where the mean molecular weight almost stays constant. The locally distorted helix regions possibly may serve as recognition sites in the first step of excision repair.

Non-enzymatic DNA strand breaks induced in mammalian cells by fluorescent light

Fluorescent light (5.4 J . m-2 . s-1) induces 0.041 single-strand breaks per 10(8) daltons per h in the DNA of cultured Chinese hamster cells (4.8 . 10(-6) breaks per 10(8) daltons per J . m-2). The breaks are induced at 1 degrees C and hence are not likely to be the result of endonuclease incision. When the cells are incubated at 37 degrees C, the breaks are rejoined within 2 h. At least two lesions are responsible for the observed effects. One lesion has the ability to break DNA subsequently treated with alkali but is neither toxic nor mutagenic. This lesion is produced by light of wavelength greater than approx. 350 nm. The other lesion(s) produce mutagenicity and/or toxicity, but do not necessarily produce strand breaks. These lesion(s) are produced by light of wavelength less than 350 nm.

Evidence for B-C transition in ultraviolet-irradiated DNA. An infrared linear dichroism study

Oriented films of calf thymus DNA are studied before and after 254 nm ultraviolet irradiation by infrared linear dichroism. The ultraviolet-irradiated DNA films are changed in their conformation, which is indicated by a replacement of the B-A transition by a B-C transition when the humidity is lowered, from 90% to 75% relative humidity.

Genetic analysis of repair of ultraviolet damage by competent and noncompetent cells of Bacillus subtilis

The repair of ultraviolet (UV) damage in Bacillus subtilis W23T(-) has been studied by transformation with deoxyribonucleic acid (DNA) extracted from irradiated cells before and after repair. The extent of repair of genetic markers by donor cells after low or moderate doses of UV was found to be related only to the initial degree of inactivation. After a very high dose, further inactivation occurred, also in proportion to initial damage. In addition, the competent recipient cells were shown to repair approximately 75% of the damage in transforming DNA. The sensitivities of markers irradiated either in vivo or in vitro appeared to be related to map position, the more proximal markers showing a greater resistance to UV inactivation.

Comparison of two transformation systems for the assay of the Neurospora photoreactivating enzyme

TheNeurospora crassaphotoreactivating enzyme has been assayed for by theHemophilus influenzaeandBacillus subtilistransformation systems. In contrast to theH. influenzaesystem, u.v.-treated transforming DNA fromB. subtilisdid not give evidence of reactivation of u.v. lesions by crude enzyme extracts fromN. crassawhen exposed to photoreactivating light. The u.v. dose required to inactivateB. subtilistransforming DNA is about ten times that required to inactivateH. influenzaeDNA to the same level of survival. This difference in dose required to inactivate DNA's of about the same base composition probably reflects the greater u.v. resistance of theB. subtilisrecipient strains used. Hypotheses are considered which suggest thatN. crassacrude enzyme extracts contain either nucleases which degradeB. subtilistransforming DNA excessively or an inhibitory factor which affects the transformation process itself.