Liver peroxisomes in newborns from clofibrate-treated rats. II. A biochemical study of the recovery period.

The fatty-acyl-CoA beta-oxidation (FAO) and catalase activities, as well as membrane fluidity of liver peroxisomes of newborns from normal and clofibrate-treated rats were studied during the recovery period, ie, throughout the first week of postnatal life. In the test animals the enzyme activities, which are significantly higher than controls at birth return to normal levels showing a somewhat different time course with FAO rapidly decreasing to control values within three days but with catalase still higher than controls at day 6. The half-life and degradation rate (Kd) of FAO are identical to those calculated by us for the whole organelles and to those reported by others for total catalase in normal or clofibrate-treated adult animals in the presence of catalase inhibitors. Soluble catalase shows turnover values which are similar though not identical to those of FAO, while total catalase has a very long half-life and a low Kd. Peroxisomal membrane fluidity, as determined by fluorescence anisotropy of 1-anilinonaphthalene-8-sulfonate (ANS) bound to purified peroxisomal fractions is higher in tests than in controls, recovering normal values within 6 days. Our results demonstrate that liver peroxisomes of rats prenatally exposed to clofibrate return to control conditions within about 1 week. The turnover parameters of enzymes and the membrane fluidity values are discussed in terms of disposal mechanism(s) for the excess of induced peroxisomes.     

Ornithine decarboxylase, transglutaminase, diamine oxidase and total diamines and polyamines in maternal liver and kidney throughout rat pregnancy.

Ornithine decarboxylase (ODC; EC 4.1.1.17), transglutaminase (EC 2.3.2.13), diamine oxidase (DAO; EC 1.4.3.6) and total di- and poly-amines were studied in rat liver and kidney cortex throughout pregnancy. In liver, ODC activity exhibited two major peaks (4.5-5 times the control activities) on days 15 and 17. Also putrescine and spermidine increased biphasically (3-4-fold), but no variation in spermine content was observed. Transglutaminase activity showed slight variations only near the end of gestation. In kidney, ODC activity did not fluctuate significantly during pregnancy, whereas both transglutaminase activity and putrescine content showed three major increases, in very early, middle and late pregnancy. No significant variations in spermidine and spermine were observed. In both organs, DAO activity, very low or undetectable until day 10, dramatically increased (10- and 20-fold in kidney and liver respectively) in the second half of pregnancy, reaching maxima on days 16-17 and 19. The results obtained for transglutaminase, ODC and total di- and poly-amines are interpreted on the basis of hyperplastic and hypertrophic events in the liver and kidney respectively. The behaviour of DAO suggests that the enzyme plays an important role in the control of intracellular diamine concentration.     

Anonymous nuclear DNA markers in the American oyster and their implications for the heterozygote deficiency phenomenon in marine bivalves

A puzzling population-genetic phenomenon widely reported in allozyme surveys of marine bivalves is the occurrence of heterozygote deficits relative to Hardy-Weinberg expectations. Possible explanations for this pattern are categorized with respect to whether the effects should be confined to protein-level assays or are genomically pervasive and expected to be registered in both protein- and DNA-level assays. Anonymous nuclear DNA markers from the American oyster were employed to reexamine the phenomenon. In assays based on the polymerase chain reaction (PCR), two DNA-level processes were encountered that can lead to artifactual genotypic scorings: (a) differential amplification of alleles at a target locus and (b) amplification from multiple paralogous loci. We describe symptoms of these complications and prescribe methods that should generally help to ameliorate them. When artifactual scorings at two anonymous DNA loci in the American oyster were corrected, Hardy-Weinberg deviations registered in preliminary population assays decreased to nonsignificant values. Implications of these findings for the heterozygote-deficit phenomenon in marine bivalves, and for the general development and use of PCR-based assays, are discussed.      

Monocarbonyl Analogs of Curcumin with Potential to Treat Colorectal Cancer

Curcumin has a plethora of biological properties, making this compound potentially effective in the treatment of several diseases, including cancer. However, curcumin clinical use is compromised by its poor pharmacokinetics, being crucial to find novel analogs with better pharmacokinetic and pharmacological properties. Here, we aimed to evaluate the stability, bioavailability and pharmacokinetic profiles of monocarbonyl analogs of curcumin. A small library of monocarbonyl analogs of curcumin 1a–q was synthesized. Lipophilicity and stability in physiological conditions were both assessed by HPLC-UV, while two different methods assessed the electrophilic character of each compound monitored by NMR and by UV-spectroscopy. The potential therapeutic effect of the analogs 1a–q was evaluated in human colon carcinoma cells and toxicity in immortalized hepatocytes. Our results showed that the curcumin analog 1e is a promising agent against colorectal cancer, with improved stability and efficacy/safety profile.     

Sporulation: an alternative way to recover recombinant proteins from Bacillus subtilis

A recombinant strain of Bacillus subtilis engineered for endocellular expression of human interleukin-1 receptor antagonist (IL-Ira) was subjected to sporulation. The recombinant protein was recovered from the sporulation supernatant in quantities, purity, and activity comparable with those obtained from a traditional cell lysate. Thus, exploitation of this natural mechanism of autolysis could overcome problems of intact protein recovery related to the cell disruption step. (c) 1995 John Wiley & Sons, Inc.     

Sampling properties of DNA sequence data in phylogenetic analysis

We inferred phylogenetic trees from individual genes and random samples of nucleotides from the mitochondrial genomes of 10 vertebrates and compared the results to those obtained by analyzing the whole genomes. Individual genes are poor samples in that they infrequently lead to the whole-genome tree. A large number of nucleotide sites is needed to exactly determine the whole-genome tree. A relatively small number of sites, however, often results in a tree close to the whole-genome tree. We found that blocks of contiguous sites were less likely to lead to the whole-genome tree than samples composed of sites drawn individually from throughout the genome. Samples of contiguous sites are not representative of the entire genome, a condition that violates a basic assumption of the bootstrap method as it is applied in phylogenetic studies.      

The biology of the heat shock response in parasites

The heat shock response is a general homeostatic mechanism that protects cells and the entire organism from the deleterious effects of environmental stress. It has been shown that heat shock proteins play major roles in many cellular processes and have a unique role in several areas of cell biology, from chronic degenerative diseases to immunology and from cancer research to interactions between host and parasite. In this review, Bruno Maresca and Luisella Carratu deal with some of the unique characteristics of the heat shock response in parasitic organisms.     

Crystal Structure of the Hendra Virus Attachment G Glycoprotein Bound to a Potent Cross-Reactive Neutralizing Human Monoclonal Antibody

The henipaviruses, represented by Hendra (HeV) and Nipah (NiV) viruses are highly pathogenic zoonotic paramyxoviruses with uniquely broad host tropisms responsible for repeated outbreaks in Australia, Southeast Asia, India and Bangladesh. The high morbidity and mortality rates associated with infection and lack of licensed antiviral therapies make the henipaviruses a potential biological threat to humans and livestock. Henipavirus entry is initiated by the attachment of the G envelope glycoprotein to host cell membrane receptors. Previously, henipavirus-neutralizing human monoclonal antibodies (hmAb) have been isolated using the HeV-G glycoprotein and a human naïve antibody library. One cross-reactive and receptor-blocking hmAb (m102.4) was recently demonstrated to be an effective post-exposure therapy in two animal models of NiV and HeV infection, has been used in several people on a compassionate use basis, and is currently in development for use in humans. Here, we report the crystal structure of the complex of HeV-G with m102.3, an m102.4 derivative, and describe NiV and HeV escape mutants. This structure provides detailed insight into the mechanism of HeV and NiV neutralization by m102.4, and serves as a blueprint for further optimization of m102.4 as a therapeutic agent and for the development of entry inhibitors and vaccines.     

Genetic differentiation of the Euglossini (Hymenoptera, Apidae) populations on a mainland coastal plain and an island in southeastern Brazil

Euglossini bees are among the main pollinators of plant species in tropical and subtropical forests in Central and South America. These bees are known as long-distance pollinators due to their exceptional flight performance. Here we assessed through microsatellite loci the gene variation and genetic differentiation between populations of four abundant Euglossini species populations sampled in two areas, Picinguaba (mainland) and Anchieta Island, Ubatuba, São Paulo State, southeastern Brazil. There was no significant genetic differentiation between the island and mainland samples of Euglossa cordata (Fst = 0.008, P = 0.60), Eulaema cingulata (Fst = 0.029, P = 0.29) and Eulaema nigrita (Fst = 0.062, P = 0.38), but a significant gene differentiation between mainland and island samples of Euglossa stellfeldi (Fst = 0.028, P = 0.016) was detected. As expected, our results showed that the water body that separates the island from the mainland does not constitute a geographic barrier for these Euglossini bees. The absence of populational structuring of three out the four species studied corroborates previous reports on those bees, characterized by large populations, with high gene diversity and gene flow and very low levels of diploid males. But the Eg. stellfeldi results clearly point that dispersal ability is not similar to all euglossine bees, what requires the development of different conservationist strategies to the Euglossini species.