Survivorship and food consumption of immatures and adults of Apis mellifera and Scaptotrigona bipunctata exposed to genetically modified eucalyptus pollen.

Eucalyptus comprises the largest planted area of cultivated production forest in Brazil. Genetic modification (GM) of eucalyptus can provide additional characteristics for increasing productivity and protecting wood yield, as well as potentially altering fiber for a diversity of industrial uses. However, prior to releasing a new GM plant, risk assessments studies with non-target organisms must be undertaken. Bees are prominent biological models since they play an important role in varied ecosystems, including for Eucalyptus pollination. The main goal of this study was to evaluate whether a novel event (Eucalyptus 751K032), which carries the cp4-epsps gene that encodes the protein CP4-EPSPS and nptII gene that encodes the protein NPTII, might adversely affect honey bees (Apis mellifera) and stingless bees (Scaptotrigona bipunctata). The experiments were performed in southern Brazil, as follows: (i) larvae and adults were separately investigated, (ii) three or four different pollen diets were offered to bees, depending on larval or adult status, and (iii) two biological attributes, i.e., survivorship of larvae and adults and food intake by adults were evaluated. The diets were prepared with pollen from GM Eucalyptus 751K032; pollen from conventional Eucalyptus clone FGN-K, multifloral pollen or pure larval food. The insecticide dimethoate was used to evaluate the sensitivity of bees to toxic substances. Datasets were analyzed with Chi-square test, survival curves and repeated measures ANOVA. Results indicated no evidence of adverse effects of Eucalyptus pollen 751K032 on either honey bees or stingless bees assessed here. Therefore, the main findings suggest that the novel event may be considered harmless to these organisms since neither survivorship nor food consumption by bees were affected by it.

Bioengineered II-VI semiconductor quantum dot-carboxymethylcellulose nanoconjugates as multifunctional fluorescent nanoprobes for bioimaging live cells.

Colloidal semiconductor quantum dots (QDs) are light-emitting ultra-small nanoparticles, which have emerged as a new class of nanoprobes with unique optical properties for bioimaging and biomedical diagnostic. However, to be used for most biomedical applications the biocompatibility and water-solubility are mandatory that can achieved through surface modification forming QD-nanoconjugates. In this study, semiconductor II-VI quantum dots of type MX (M=Cd, Pb, Zn, X=S) were directly synthesized in aqueous media and at room temperature using carboxymethylcellulose sodium salt (CMC) behaving simultaneously as stabilizing and surface biofunctional ligand. These nanoconjugates were extensively characterized using UV-visible spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, dynamic light scattering and zeta potential. The results demonstrated that the biopolymer was effective on nucleating and stabilizing the colloidal nanocrystals of CdS, ZnS, and PbS with the average diameter ranging from 2.0 to 5.0nm depending on the composition of the semiconductor core, which showed quantum-size confinement effect. These QD/polysaccharide conjugates showed luminescent activity from UV-visible to near-infrared range of the spectra under violet laser excitation. Moreover, the bioassays performed proved that these novel nanoconjugates were biocompatible and behaved as composition-dependent fluorescent nanoprobes for in vitro live cell bioimaging with very promising perspectives to be used in numerous biomedical applications and nanomedicine.

Carboxymethylcellulose/ZnCdS fluorescent quantum dot nanoconjugates for cancer cell bioimaging.

In this study, it is reported the use of sodium carboxymethyl cellulose (CMCel) as a multifunctional biocompatible polysaccharide for the direct synthesis of fluorescent alloyed-ZnCdS quantum dot (QD) nanoconjugates via aqueous "green" process at room temperature. The nanoconjugates were extensively characterized by spectroscopical (NMR, FTIR, UV-vis, PL) and morphological techniques (DLS, TEM) for accessing their structural and physicochemical properties associated with X-ray photoelectron spectroscopy (XPS) for surface and interface analysis. The results proved the hypothesis of formation of core-shell nanostructures composed by the semiconductor ZnCdS QD core and the organic biocompatible ligand CMCel shell. Moreover, CMCel chemical functional groups played a pivotal role for controlling the size of water-soluble colloidal nanocrystals (2r=4-5nm) and hydrodynamic diameters (<15nm) evidenced by metal complexation and interactions at the nanointerfaces. Additionally, these nanoconjugates were cytocompatible and luminescent for bioimaging human osteosarcoma cancer cells. Thus, these novel polysaccharide-based fluorescent bioconjugates offer promising perspectives as nanoplatforms for cancer cell bioimaging and diagnosis purposes.