Decreased tumor growth in Walker 256 tumor-bearing rats chronically supplemented with fish oil involves COX-2 and PGE2 reduction associated with apoptosis and increased peroxidation

Many studies have shown that addition of fish oil (FO) to the diet reduces tumor growth but the mechanism(s) of action involved is (are) still unknown. In this study, we examine some possible mechanisms in tumor-bearing rats chronically supplemented with FO. Male Wistar rats (21 days old) were fed with regular chow and supplemented with coconut or FO (1g/kg body weight) until they reached 70 days of age. Then, they were inoculated with a suspension of Walker 256 ascitic tumor cells (2 x 10(7)ml) and after 14 days they were killed. Supplementation with FO resulted in significantly lower tumor weight, greater tumor cell apoptosis, lower ex vivo tumor cell proliferation, a higher tumor content of lipid peroxides, lower expression of cyclooxygenase-2 (COX-2) in tumor tissue and a lower plasma concentration of prostaglandin E2 than observed in rats fed regular chow or supplemented with coconut oil. These results suggest that reduction of tumor growth by FO involves an increase in apoptosis and of lipid peroxidation in tumor tissue, with a reduction in tumor cell proliferation ex vivo, COX-2 expression and PGE2 production. Thus, FO may act simultaneously through multiple effects to reduce tumor growth. Whether these effects are connected through a single underlying mechanism remains to be seen.     

Molecular phylogeny of the South American land slug Phyllocaulis (Mollusca,Soleolifera, Veronicellidae)

Gomes, S. R., Britto da Silva, F., Mendes, I. L. V., Thomé, J. W. & Bonatto, S. L. (2009). Molecular phylogeny of the South American land slug Phyllocaulis (Mollusca, Soleolifera, Veronicellidae). —Zoologica Scripta, 39, 177–186. Our main objectives were investigate the phylogenetic relationships between the species of the land slug Phyllocaulis and the monophyly of the genus based on mitochondrial (16S and COI) and nuclear (ITS2) DNA sequences from multiple individuals from each species. Evolutionary trees were constructed using Bayesian inference, maximum likelihood, maximum parsimony and neighbor‐joining methods. All species accepted in the current taxonomy based on penial characteristics and radular measurements were reciprocally monophyletic. Five species out of six formed a clade with the following highly supported relationship: Phyllocaulis gayi, Phyllocaulis soleiformis, Phyllocaulis renschi, Phyllocaulis variegatus, Phyllocaulis boraceiensis. The position of Vaginulus taunaisii changed according to the analysis, appearing as sister‐group of Phyllocaulis or as sister‐group of Phyllocaulis tuberculosus. Divergence times estimated from the 16S tree indicated that the extant species of Phyllocaulis shared a common ancestor around 1.3 Ma and that most species originated between 0.8 and 0.6 Ma.     

Differentiation of human adipose-derived adult stem cells into neuronal tissue: Does it work?

Adipose tissue contains many cells and proteins that are of value not only for their potential therapeutic applications, but also for the low cost of their harvest and delivery. Mesenchymal stem cells (MSC) were originally isolated from the bone marrow, although similar populations have been isolated from adipose and other tissues. At one time, neural tissues were not regarded as regenerative populations of cells. Therefore, the identification of cell populations capable of neuronal differentiation has generated immense interest. Adipose tissue may represent an alternative source of cells that are capable of neuronal differentiation, potentially enhancing its use in the treatment of neurological disease. The aim of this review is to cover the current state of knowledge of the differentiation potential of human adipose-derived stem (ADAS) cells, specifically their ability to give rise to neuronal cells in vitro. This review presents and discusses different protocols used for inducing human ADAS cells to differentiate in vitro, and the neuronal markers utilized in each system.     

Injection tube differentiation in gun cells of a haptoglossa species which infects nematodes

The gun cells which develop from germinating cysts in Haptoglossa produce a specialized infection apparatus, the injection tube. Upon eversion this tube fires a missile-like projectile which penetrates the host cuticle and then forms an infective sporidium within the body cavity of the nematode host. The temporal assembly of this complex cell organelle has been determined by serial-section reconstructions of maturing gun cells in a previously undescribed Haptoglossa species. The differentiation of the partially walled inverted injection tube is an unusual example of internal tube growth, in which membrane and wall assembly are temporally separated. There is no evidence that the shape of this inverted tube, which coils around the nucleus until it doubles back on itself, is dictated by the disposition of cytoplasmic microtubules. However, actin-like material was associated with the delimiting membrane of the differentiating tube, particularly in the regions of extension. From these studies it seems likely that the "head and buttress" structures previously depicted as the barbed tip of the "harpoon-like" penetration missile are part of a separate, structurally complex system which we suggest locks the "missile" into position in the invaginated injection tube. From this detailed account of cell architecture, models for the likely mechanism of infection cell firing are discussed, and unresolved questions relating to the cell biology and biochemistry of these complex organelles are highlighted. Copyright 1998 Academic Press.     

Replication process of the parvovirus H-1. VIII. Partial denaturation mapping and localization of the replication origin of H-1 replicative-form DNA with electron microscopy.

Partial denaturation mapping, restriction endonuclease digestion, and electron microscopy were used to determine which end of the linear duplex replicative-form (RF) DNA molecule contains the origin of RF replication for the parvovirus H-1. This origin was localized within approximately 300 base pairs of the arbitrarily designated right end of the RF DNA, in the EcoRI or HaeII-A fragment. Based on denaturation behavior in formamide, the right end was also found to have a relatively high guanine plus cytosine content, whereas the region adjacent to the left terminus of the RF DNA molecule was adenine plus thymine rich.     

Relationships among carbohydrate intermediate metabolites and DNA damage and repair in yeast from a systems biology perspective

Glucose and fructose are major dietary carbohydrates that are essential for general metabolism. The elevated consumption of these two monosaccharides by the human population is related to the development of pluri-metabolic syndromes (e.g., diabetes mellitus and obesity). Glucose and fructose are metabolized by specific biochemical pathways to generate energy and metabolites. Many of these metabolites are mono- and bi-phosphorylated compounds, which renders them likely to generate reactive carbonyl species (RCS). Under physiological conditions, RCS react non-enzymatically with macromolecules and small molecules by means of Maillard reactions, forming stable glycated/fructated compounds called advanced glycation end products (AGEs). DNA and dNTPs are prone to react with RCS, forming DNA- and dNTP-AGEs, and many of these compounds are genotoxic and/or mutagenic. Unfortunately, little is understood about the genotoxicity and/or mutagenicity of carbohydrate intermediate metabolites or their interactions with DNA repair and carbohydrate metabolic-associated proteins. To elucidate these associations between carbohydrate metabolic pathways, DNA repair mechanisms, and dNTP-/DNA-AGEs, a systems biology study was performed by employing algorithms to mine literature data and construct physical protein-protein interactions. The results obtained in this work allow us to construct a model suggesting that yeast carbohydrate metabolic-associated enzymes activate different mechanisms for DNA repair and dNTP synthesis and act during DNA replication to protect the genome against the effects of RCS.     

Hidden generic diversity in Neotropical birds: molecular and anatomical data support a new genus for the "Scytalopus"indigoticus species-group (Aves: Rhinocryptidae)

The genus Scytalopus is a species-rich and taxonomically complicated component of the Neotropical avian family Rhinocryptidae. Probably because Scytalopus is a superficially uniform assemblage, its monophyly has not been seriously questioned. We investigated phylogenetic relationships of a representative set of species in the genus using nuclear and mitochondrial DNA sequences as well as anatomical data, and provided the first test of its presumed monophyly by including in the analyses its hypothesized closest relatives (the genera Myornis, Eugralla, and Merulaxis) as well as most rhinocryptid genera. We found strong support for the paraphyly of the genus Scytalopus, with the Scytalopus indigoticus species-group forming a clade with Merulaxis. A well-supported clade including the genera Eugralla, Myornis, and the remaining Scytalopus was also recovered. Because these results were recovered independently and with strong support using mitochondrial and nuclear data, and were entirely consistent with anatomical data, we erect a new genus for the S.indigoticus species-group. These findings illustrate the importance of formally testing hypotheses of monophyly even for well-accepted groups of Neotropical birds.     

Role of PSO genes in repair of DNA damage of Saccharomyces cerevisiae

Photoactivated psoralens used in treatment of skin diseases like Psoriasis and Vitiligo cause DNA damage, the repair of which may lead to mutations and thus to higher risk to have skin cancer. The simple eukaryote Saccharomyces cerevisiae was chosen to investigate the cells' genetic endowment with repair mechanisms for this type of DNA damage and to study the genetic consequences of such repair. Genetic studies on yeast mutants sensitive to photoactivated psoralens, named pso mutants, showed their allocation to 10 distinct loci. Cloning and molecular characterization allowed their grouping into three functional classes: (I) the largest group comprises seven PSO genes that are either generally or specifically involved in error-prone DNA repair and thus affect induced mutability and recombination; (II) one PSO gene that represents error-free excision repair, and (III) two PSO genes encoding proteins not influencing DNA repair but physiological processes unrelated to nucleic acid metabolism. Of the seven DNA repair genes involved in induced mutagenesis three PSO loci [PSO1/REV3, PSO8/RAD6, PSO9/MEC3] were allelic to already known repair genes, whereas three, PSO2/SNM1, PSO3/RNR4, and PSO4/PRP19 represent new genes involved in DNA repair and nucleic acid metabolism in S. cerevisiae. Gene PSO2 encodes a protein indispensable for repair of interstrand cross-link (ICL) that are produced in DNA by a variety of bi- and polyfunctional mutagens and that appears to be important for a likewise repair function in humans as well. In silico analysis predicts a putative endonucleolytic activity for Pso2p/Snm1p in removing hairpins generated as repair intermediates. The absence of induced mutation in pso3/rnr4 mutants indicates an important role of this subunit of ribonucleotide reductase (RNR) in regulation of translesion polymerase zeta in error-prone repair. Prp19p/Pso4p influences efficiency of DNA repair via splicing of pre-mRNAs of intron-containing repair genes but also may function in the stability of the nuclear scaffold that might influence DNA repair capacity. The seventh gene, PSO10 which controls an unknown step in induced mutagenesis is not yet cloned. Two genes, PSO6/ERG3 and PSO7/COX11, are responsible for structural elements of the membrane and for a functional respiratory chain (RC), respectively, and their function thus indirectly influences sensitivity to photoactivated psoralens.