BODIPY for photodynamic therapy applications: computational study of the effect of bromine substitution on <Superscript>1</Superscript>O<Subscript>2</Subscript> photosensitization

Density functional theory and its time-dependent extension (DFT, TDDFT) were employed to establish the feasibility of using a series of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacenes (BODIPYs) in photodynamic therapy. Their absorption electronic spectra, singlet–triplet energy gaps, and spin–orbit matrix elements were computed and are discussed here. The effects of bromine substitution on the photophysical properties of BODIPY were elucidated. The investigated compounds were found to possess different excited triplet states that lie below the energy of the bright excited singlet state (S₁ or S₂), depending on the positions occupied by the bromine atoms. The computed spin–orbit matrix elements for the radiationless intersystem crossing S_n?→ ?T_m and the relative singlet–triplet energy gaps allowed the prediction of plausible nonradiative decay pathways for the production of singlet excited molecular oxygen, the key cytotoxic agent in photodynamic therapy.

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Graphical Abstract The photophysical properties affected by the presence of bromine atoms in different positions of a BODIPY core have been here elucidated. In particular it has been found that SOC values strongly depend on the position of heavy atoms into the BODIPY core, suggesting positions 1 and 7 as the best ones to enhance the ISC kinetics

     

Babassu palm (Attalea speciosa Mart.) super-dominance shapes its surroundings via multiple biotic,soil chemical,and physical interactions and accumulates soil carbon: a case study in eastern Amazonia

Plant and Soil - Aggressive ruderal plant species pose an increasing problem in anthropically degraded lands. They both affect and are affected by other vegetation and by soil fertility in their...     

Evaluation of Moringa oleifera seed flour as a flocculating agent for potential biodiesel producer microalgae

Microalgal biofuel alternatives have been hindered by their cost and energy intensive production. In the microalgal harvesting process, the intermediate step of flocculation shows potential in drastically reducing the need for costly centrifugation processes. Moringa oleifera seeds, which have been used for water treatment due to their high flocculation potential, low cost and low toxicity, are presented in this paper as strong candidate for flocculating Chlorella vulgaris, a microalgae with high biodiesel production potential. Early results of our group showed a very high flocculation (around 85% of biomass recovery). The aim of this work was to investigate the influence of Moringa oleifera seed flour concentration, sedimentation time and pH on the flocculation efficiency. Cell suspensions treated with Moringa seed flour (1 g L^-1) had their flocculation significantly increased with the rise of pH, reaching 89% of flocculation in 120 min at pH 9.2. Sedimentation time of 120 min and a concentration of 0.6 g L^-1 proved to be ample for substantial flocculation efficiency. In spite of the need for more research to ensure the economic viability and sustainability of this process, these results corroborate Moringa oleifera seeds as a strong candidate as a bioflocculant for Chlorella vulgaris cells and indicate optimal pH range of its action.     

Elongating modified conserved peptides eliminates their immunogenicity and protective efficacy against P. falciparum malaria

Plasmodium falciparum malaria protein peptides were synthesised in the search for more effective routes for inducing a protective immune response against this deadly parasite and this information has been associated with such molecules' three-dimensional structure. These peptides had high red blood cell binding activity and their carboxy- and amino-terminal extremes were elongated for determining their immunogenic and protection-inducing activity against this disease in the Aotus monkey experimental model. 1H-NMR was used for analysing their three-dimensional structure; FAST ELISA, immunofluorescence antibody test, and Western blot were used for identifying their antibody inducing capacity and these previously immunised Aotus were inoculated with a highly infective P. falciparum strain to determine whether these elongated peptides were able to induce protection. This was aimed at establishing an association or correlation between long peptides' three-dimensional structure and their immunogenic and protection-inducing response in these monkeys. Peptides 20026 (25 residue), 20028 (30 residue), and 20030 (35 residues) were synthesised based on elongating the amino-terminal region of the 10022 highly immunogenic and protection-inducing modified peptide. 1H-NMR studies revealed that the first three had Classical type III beta-turn structures, different from the 20-amino acid long modified peptide 10022 which had a distorted type III beta-turn. Humoral immune response analysis showed that even when some antibodies could be generated against the parasite, none of the immunised Aotus could be protected with elongated peptides suggesting that elongating them eliminated modified peptide 10022 immunogenic and protection-inducing capacity.     

Degradation of the methyl substituted alkene, citronellol, by Pseudomonas aeruginosa, wild type and mutant strains

Pseudomonas aeruginosa W51D used citronellol (3,7-dimethyl-6-octen-1-ol) as sole source of carbon and oxidized it to citronellal, citronellic acid and finally to geranic acid. A mutant derived from this strain was isolated as unable to degrade citronellol and had diminished (93%) citronellal dehydrogenase activity.     

Expression of the alpha3/beta1 isoform of human Na,K-ATPase in the methylotrophic yeast Pichia pastoris

Na,K-ATPase is a crucial enzyme for ion homeostasis in human tissues. Different isozymes are produced by assembly of four alpha- and three beta-subunits. The expression of the alpha3/beta1 isozyme is confined to brain and heart. Its heterologous production has so far never been attempted in a lower eukaryote. In this work we explored whether the methylotrophic yeast Pichia pastoris is capable of expressing the alpha3/beta1 isoform of human Na,K-ATPase. cDNAs encoding the alpha(3) and the beta(1)-subunits were cloned under the control of the inducible promoter of Pichia pastoris alcohol oxidase 1. Pichia pastoris could express the single alpha3- and beta1-subunits and even coexpress them after methanol induction. beta1-subunit was produced as a major 44-kDa glycosylated polypeptide and alpha3 as a 110-kDa unglycosylated polypeptide. Expression at the plasma membrane was limited in shaking flask cultures but by cultivating P. pastoris cells in a fermenter there was a 10-fold increase of the number of ouabain binding sites per cell. The exported enzyme was estimated to be about 0.230 mg L(-1) at the end of a bioreactor run. Na,K-ATPase proved active and the dissociation constant of the recombinant enzyme-ouabain interaction was determined.     

Biological and genetic aspects of crosses between species of the genus Meccus (Hemiptera: Reduviidae Triatominae)

The degree of reproductive isolation between Meccus phyllosomus and the remaining five species of the genus Meccus, as well as between Meccus bassolsae and Meccus pallidipennis, Meccus longipennis and Meccus picturatus, was examined. Fertility and the segregation of morphological characteristics were examined in two generations of hybrids from crosses between these species. The percentage of couples with offspring (fertile) was high in the vast majority of sets of crosses, with the exception of that between ♀M. phyllosomus and ♂Meccus mazzottii. In sets of crosses involving M. bassolsae specimens, no first-generation (F1) individuals were morphologically similar to M. bassolsae, but instead shared the morphology of the other parental species. A similar phenomenon was observed in most sets of crosses involving M. phyllosomus. These results indicated that different degrees of reproductive isolation exist among the species of Meccus involved in this study. The biological evidence obtained in this study does not support the proposal that M. bassolsae is a full species. It could indicate that, on the contrary, it should be considered a subspecies of a single polytypic species. The biological evidence does support the proposal that M. phyllosomus is a full species.     

Role of HSP101 in the stimulation of nodal root development from the coleoptilar node by light and temperature in maize (Zea mays L.) seedlings

Nodal roots (NRs) constitute the prevalent root system of adult maize plants. NRs emerge from stem nodes located below or above ground, and little is known about their inducing factors. Here, it is shown that precocious development of NRs at the coleoptilar node (NRCNs) occurred in maize seedlings when: (i) dark grown and stimulated by the concurrent action of a single light shock of low intensity white light (2 μmol m(-2) s(-1)) and a single heat shock; (ii) grown under a photoperiod of low intensity light (0.1 μmol m(-2) s(-1)); or (iii) grown in the dark under a thermoperiod (28 °C/34 °C). The light shock effects were synergistic with heat shock and with the photoperiod, whereas the thermoperiodical and photoperiodical effects were additive. Dissection of the primary root or the root cap, to mimic the fatal consequences of severe heat shock, caused negligible effects on NRCN formation, indicating that the shoot is directly involved in perception of the heat shock-inducible signal that triggered NRCN formation. A comparison between hsp101-m5::Mu1/hsp101-m5::Mu1 and Hsp101/Hsp101 seedlings indicated that the heat shock protein 101 (HSP101) chaperone inhibited NRCN formation in the light and in the dark. Stimulation of precocious NRCN formation by light and heat shocks was affected by genetic background and by the stage of seedling development. HSP101 protein levels increased in the coleoptilar node of induced wild-type plants, particularly in the procambial region, where NRCN formation originated. The adaptive relevance of development of NRCNs in response to these environmental cues and hypothetical mechanisms of regulation by HSP101 are discussed.