Carbon coated magnetic nanoparticles for local drug delivery using magnetic implants

Bioferrofluids obtained from carbon coated iron nanoparticles are promising candidates for magnetic drug delivery. The carbon cages render the particles biocompatible, and provide a good support for drug adsorption. We propose a method in which gold plated permanent magnets are implanted directly in the affected organ, close to the tumour, by endoscopic techniques. The bioferrofluid charged with the chemotherapeutic agent is injected and the particles attracted to the magnet, then desorption of the drug takes place at the tumoral region. This method seems to be more promising, costless and effective than that based on the application of external magnetic fields. Preliminary results of drug adsorption and a preclinical experimental animal model are described.     

Hansenula polymorpha Vam7p is required for macropexophagy

We have analyzed the functions of two vacuolar t-SNAREs, Vam3p and Vam7p, in peroxisome degradation in the methylotrophic yeast Hansenula polymorpha. A Hp-vam7 mutant was strongly affected in peroxisome degradation by selective macropexophagy as well as non-selective microautophagy. Deletion of Hp-Vam3p function had only a minor effect on peroxisome degradation processes. Both proteins were located at the vacuolar membrane, with Hp-Vam7p also having a partially cytosolic location. Previously, in baker's yeast Vam3p and Vam7p have been demonstrated to be components of a t-SNARE complex essential for vacuole biogenesis. We speculate that the function of this complex in macropexophagy includes a role in membrane fusion processes between the outer membrane layer of sequestered peroxisomes and the vacuolar membrane. Our data suggest that Hp-Vam3p may be functionally redundant in peroxisome degradation. Remarkably, deletion of Hp-VAM7 also significantly affected peroxisome biogenesis and resulted in organelles with multiple, membrane-enclosed compartments. These morphological defects became first visible in cells that were in the mid-exponential growth phase of cultivation on methanol, and were correlated with accumulation of electron-dense extensions that were connected to mitochondria.     

Cyclic Peptides Containing Biaryl and Biaryl Ether Linkages

This review describes the isolation, activities and synthetic approaches of the naturally occurring cyclic peptides containing biaryl and/or biaryl ether linkages. These compounds range from monocyclic, to bicyclic, to the polycyclic glycopeptide antibiotics, and most of them exhibit significant biological properties such as cytotoxic or antimicrobial activities. Interestingly, vancomycin is used clinically as the antibiotic of last resort for the treatment of methicillin-resistant Staphylococcus aureus. The medicinal significance and the structural complexity of these macrocycles have challenged chemists towards the total synthesis of these compounds and in designing synthetic analogues. Non-natural macrocycles reported from 1999 to 2004 are also covered.     

Complete Reversal of Coenzyme Specificity of Isocitrate Dehydrogenase from <Emphasis Type="Italic">Haloferax volcanii</Emphasis>

Haloferax volcanii Ds-threo-isocitrate dehydrogenase (ICDH) was highly expressed in bacteria as inclusion bodies. The recombinant enzyme was refolded, purified and characterized, and was found to be NADP-dependent like the wild-type protein. Sequence alignment of several isocitrate dehydrogenases from evolutionarily divergent organisms including H. volcanii revealed that the amino acid residues involved in coenzyme specificity are highly conserved. Our objective was to switch the coenzyme specificity of halophilic ICDH by altering these conserved amino acids. We were able to switch coenzyme specificity from NADP⁺ to NAD⁺ by changing five amino acids by site-directed mutagenesis (Arg291, Lys343, Tyr344, Val350 and Tyr390). The five mutants of ICDH were overexpressed in Escherichia coli as inclusion bodies and each recombinant ICDH protein was refolded and purified, and its kinetic parameters were determined. Coenzyme specificity did not switch until all five amino acids were substituted.     

Assessments of somaclonal variation in micropropagated shoots of <Emphasis Type="Italic">Cedrus</Emphasis>: consequences of axillary bud breaking

Reversed-phase HPLC analysis and random amplified polymorphic DNA (RAPD) markers were used to monitor DNA methylation status and genetic stability of C. atlantica and C. libani shoots generated through axillary bud proliferation. Average DNA methylation in C. atlantica or C. libani seedlings and mature 200-year-old trees of C. libani was 19.8, 19.5 and 22.3%, respectively. These global amounts showed no significant variation after the in vitro establishment of seedling-originated shoot stocks. In contrast, in vitro culture caused a significant decrease in the amount of 5-methylcytosine in genomic DNA of the tissue culture (TC) progenies of one of the adult C. libani genotypes. This DNA demethylation event accompanied an enhancement of the regrowth capacity of this genotype. Detected RAPD variation between mother plants and their TC progenies was species-related, with C. libani TC progenies being genetically more stable than those of C. atlantica. Nevertheless, similarity indices ranged from 0.97 to 1 among mother plants and their TC progenies. Furthermore, the analyses of molecular variance (AMOVA) suggest that RAPD variation among the mother plants and their TC progenies might be considered as not significant. The application of various statistical approaches, including cluster-based genetic distance methods and AMOVA, demonstrates that RAPD markers discriminate C. atlantica and C. libani appropriately.     

Molecular models of protein kinase 6 from Plasmodium falciparum

Cyclin-dependent kinases (CDKs) have been identified as potential targets for development of drugs, mainly against cancer. These studies generated a vast library of chemical inhibitors of CDKs, and some of these molecules can also inhibit kinases identified in the Plasmodium falciparum genome. Here we describe structural models for Protein Kinase 6 from P. falciparum (PfPK6) complexed with Roscovitine and Olomoucine. These models show clear structural evidence for differences observed in the inhibition, and may help designing inhibitors for PfPK6 generating new potential drugs against malaria. Figure Ribbon diagram of PfPK6 complexed with a roscovitine and b olomoucine     

A taxonomic review of the nivicolous species of myxomycetes described by Kowalski. I. Order Stemonitales

Five type specimens of species from the order Stemonitales proposed by Kowalski are re-examined. These are Comatricha fusiforme, Diacheopsis effusa, D. serpula, Lamproderma acanthosporum and L. disseminatum. SEM and LM micrographs of spores, capillitia and sporocarps are provided. Critical study of these type specimens supports Kowalski’s recognition of these taxa as good and valid species.     

Genetic characterization of European-Zebu composite bovine using RFLP markers

A population of 370 European-Zebu composite beef heifers, consisting of six different breed compositions (A-F), were characterized genetically, using RFLP markers of luteinizing hormone receptor (LHR) and follicle-stimulating hormone receptor (FSHR) genes. Our objectives were to genetically characterize this population and to determine the structure and the genetic variability of this hybrid herd. The genotypes were determined through PCR, followed by digestion with restriction endonucleases. The PCR-RFLP analysis made it possible to identify the LHR and FSHR genotypes, as well as to characterize the degree of heterozygosis, which was high for all of the breed compositions, for both loci, except for two combinations for LHR (B and C). The observed heterozygosity (Ho) was lower than the expected heterozygosity (He) for compositions C (for LHR) and A and D (for FSHR); however, for the population as a whole, Ho was above He (with a mean of 57 versus 46%, respectively), reflecting the elevated genetic variability in this population and also the informative value of the RFLP markers, which could be useful for population genetic characterization studies. The analysis of the degree of genetic structure of this population, estimated by the Nei's statistic, for both loci, indicated an elevated total genetic diversity (HT = 47%), with most of this variability being due to intrapopulational diversity (HS = 46%), with a low degree of genetic differentiation among the six breed compositions (GST = 1.2%). The estimates generated by the Wright's F statistic indicated a non-endogamic population, with excess heterozygotes (FIT = -0.22), which was also observed at the intrapopulational level (FIS = -0.23). The results gave evidence that the genetic selection applied to this European-Zebu composite population did not affect the expected high genetic variability for this type of crossbreeding, which makes it possible to use these animals to obtain economically valuable productive and reproductive traits.