Dissecting planarian central nervous system regeneration by the expression of neural-specific genes

The planarian central nervous system (CNS) can be used as a model for studying neural regeneration in higher organisms. Despite its simple structure, recent studies have shown that the planarian CNS can be divided into several molecular and functional domains defined by the expression of different neural genes. Remarkably, a whole animal, including the molecularly complex CNS, can regenerate from a small piece of the planarian body. In this study, a collection of neural markers has been used to characterize at the molecular level how the planarian CNS is rebuilt. Planarian CNS is composed of an anterior brain and a pair of ventral nerve cords that are distinct and overlapping structures in the head region. During regeneration, 12 neural markers have been classified as early, mid-regeneration and late expression genes depending on when they are upregulated in the regenerative blastema. Interestingly, the results from this study show that the comparison of the expression patterns of different neural genes supports the view that at day one of regeneration, the new brain appears within the blastema, whereas the pre-existing ventral nerve cords remain in the old tissues. Three stages in planarian CNS regeneration are suggested.     

The bloodsucking arthropod bite as possible cofactor in the transmission of human herpesvirus-8 infection and in the expression of Kaposi's sarcoma disease

Based on a review of the literature on human herpesvirus-8 (HHV8) and Kaposi's sarcoma (KS) and on the distribution of KS in Italy (Veneto region particularly), we hypothesize that the bite of bloodsucking arthropods is a cofactor in the seroconversion to HHV8 positivity and probably in the pathogenesis of KS. The bloodsucking arthropod releases with saliva powerful antihaemostatics and immunomodulators which may favour the replication and the establishment of the pathogen. Transmission would depend on the close contact of the child with a seropositive mother (or relatives) whose infective saliva is used to relieve itching and scratching at the arthropod bite's sites. During any deregulation of the immune system (e.g. ageing), local immune responses to new insect bites may induce virus activation which could prelude KS insurgence. The pathogen is not directly transmitted by the arthropod which merely prepares the cutaneous microenvironment for the virus. We have therefore introduced a new category of medically important arthropods, "promoter arthropods", besides those already defined as biological or mechanical vectors. Promoter arthropods are species able to induce in the host long-lasting, immediate or delayed-type hypersensitivity responses as well as local immunosuppression due to substances injected with their saliva. The striking variability of ORF-K1 gene of HHV8 could be due to the adaptation of the virus to the specific microenvironments resulting from the immune response to the salivary antigens characteristic of the bloodsucking arthropod species prevalent in each geographical area. It is worth noting that other viruses (especially Hepatitis B Virus) may exploit the same non-sexual transmission route.     

Paraoxonase1-192 polymorphism modulates the effects of regular and acute exercise on paraoxonase1 activity

Regular exercise practise is a protective factor against coronary heart disease and enhances antioxidant systems, whereas acute exercise appears to be a major source of increased oxidative stress. Paraoxonase1 (PON1) is an antioxidant HDL-linked enzyme, whose activity toward paraoxon (PON1 activity) is strongly modulated by the PON1-192 polymorphism, comprising Q and R alleles for low and high PON1 activity, respectively. Another polymorphism at the PON1 locus, the PON1-55, modulates PON1 protein and activity levels. PON1 activity, lipid levels, and oxidized LDL concentration were determined in 17 healthy young volunteers before and after a 16-weeks aerobic exercise training period. Furthermore, PON1 activity was analyzed after a bout of exercise in both situations. We found that regular exercise was associated with a decrease in oxidized LDL levels, and an increase in PON1 activity in QQ subjects and with a decrease in PON1 activity in R carriers. A bout of exercise produced an increase in PON1 activity just after the bout of exercise, followed by a decrease in its activity. A recovery of the basal PON1 activity levels at 24 h was found in QQ subjects regardless of their training status and in trained R carriers, but not in untrained R carriers. These results suggest that the effects of regular and acute exercise on PON1 activity levels are modulated by PON1-192 polymorphism. Changes were less evident for the PON1-55 polymorphism.     

Lead induced DNA strand breaks in lymphocytes of exposed workers: role of reactive oxygen species and protein kinase C

Lead and lead compounds play a significant role in modern industry; a wide variety of population is at risk of occupational exposure and lead is suspected to be a human carcinogen. The biochemical and molecular mechanisms of lead toxicity are poorly understood, but emerging data suggest that some of the effects of lead may be due to its interference with calcium in the activation of protein kinase C (PKC) and/or through production of reactive oxygen species (ROS). Many of these results are conducted in vitro on cell lines or ex vivo on human lymphocytes treated in vitro. We, therefore, performed a study on the induction of DNA damage, using the alkaline comet assay, in lymphocytes of battery plant workers. To elucidate in vivo the mechanism(s) responsible for this effect, we determined ROS production, and glutathione (GSH) levels in living cells using the fluorescent probe (2',7'-dichlorofluorescein and monochlorobimane, respectively). Subcellular fractions were obtained from sonicated lymphocytes; cytosolic and membrane expression of PKC isoforms (alpha, and zeta) was evaluated after electrophoresis by immunoblot analysis. The results indicate that lead-exposed workers have significantly elevated levels of DNA breaks compared to the unexposed group. A multivariate analysis of variance (ANOVA) shows that the most common confounding factors (smoking, drinking and age) have no synergistic effects with lead-exposure on the comet parameters or on GSH levels and ROS production. The logistic regression analysis distinguishing the exposed and non-exposed indicates that only GSH with tail moment are selected as significant risk factors. There is a significant positive correlation with ROS production and negative correlation with GSH levels. The content of PKC alpha in cytosol and membranes is decreased 40% (indicating a down-regulation of protein), whereas PKC zeta isoform is not modified in an evident manner. Our results suggest that lead-exposure induces an increase of DNA breakage with an alternate cellular redox state and a significant down-regulation of PKC alpha, suggesting that this metal may act as a tumor promoter.     

Structural properties of a collagenous heterotrimer that mimics the collagenase cleavage site of collagen type I

Collagens contain sequence- and conformation-dependent epitopes responsible for their digestion by collagenases at specific loci. A synthetic heterotrimer construct containing the collagenase cleavage site of collagen type I was found to mimic perfectly native collagen in terms of selectivity and mode of enzymatic degradation. The NMR conformational analysis of this molecule clearly revealed the presence of two structural domains, i.e. a triple helix spanning the Gly-Pro-Hyp repeats and a less ordered portion corresponding to the collagenase cleavage site where the three chains are aligned in extended conformation with loose interchain contacts. These structural properties allow for additional insights into the very particular mechanism of collagen digestion by collagenases.     

Seroprevalence of antibodies to Neospora caninum in dogs from Spain

The prevalence of Neospora caninum antibodies was determined in sera of 139 dogs from Catalonia (northeastern Spain) using the indirect immunofluorescence antibody test (IFAT). Antibodies in the IFAT were found in 17 of 139 dogs (12.2%) with titers ranging from 1:50 to 1: 1,600. Seroprevalence was higher in dogs over 1 yr old compared with dogs younger than 1 yr (P < 0.05). No statistical difference was observed when sex, breed, purpose, or modus vivendi was compared with seropositivity. Most dogs had low antibody titers, which indicated subclinical infection in the area studied. No neosporosis-related disease was reported from any dog, although a German shepherd with an antibody titer of 1:800 showed pododermatitis. All sera were also screened using a commercial direct agglutination test (DAT). The DAT showed a similar specificity but a lower sensitivity when compared with IFAT as a reference technique.     

Characterization of low- and very-low-density hepatitis C virus RNA-containing particles

The presence of hepatitis C virus (HCV) RNA-containing particles in the low-density fractions of plasma has been associated with high infectivity. However, the nature of circulating HCV particles and their association with immunoglobulins or lipoproteins as well as the characterization of cell entry have all been subject to conflicting reports. For a better analysis of HCV RNA-containing particles, we quantified HCV RNA in the low-density fractions of plasma corresponding to the very-low-density lipoprotein (VLDL), intermediate-density lipoprotein, and low-density lipoprotein (LDL) fractions from untreated chronically HCV-infected patients. HCV RNA was always found in at least one of these fractions and represented 8 to 95% of the total plasma HCV RNA. Surprisingly, immunoglobulins G and M were also found in the low-density fractions and could be used to purify the HCV RNA-containing particles (lipo-viro-particles [LVP]). Purified LVP were rich in triglycerides; contained at least apolipoprotein B, HCV RNA, and core protein; and appeared as large spherical particles with a diameter of more than 100 nm and with internal structures. Delipidation of these particles resulted in capsid-like structures recognized by anti-HCV core protein antibody. Purified LVP efficiently bind and enter hepatocyte cell lines, while serum or whole-density fractions do not. Binding of these particles was competed out by VLDL and LDL from noninfected donors and was blocked by anti-apolipoprotein B and E antibodies, whereas upregulation of the LDL receptor increased their internalization. These results suggest that the infectivity of LVP is mediated by endogenous proteins rather than by viral components providing a mechanism of escape from the humoral immune response.     

Taxonomic affinities of the Eppelsheim femur

The taxonomic affinities of the Eppelsheim femur, known as Paidopithex, have been unclear for more than a century. Over the years, due to similarities with Pliopithecus, some authors have considered it a large pliopithecid, while others refer to it as Dryopithecus. The issue could not be resolved, because no definitive Dryopithecus femora were available. With the discovery of the Dryopithecus laietanus skeleton from Can Llobateres (CLl 18800), it has become possible to test the attribution of the Eppelsheim femur to Dryopithecus on the basis of direct morphological and metrical comparisons. By means of allometric techniques, we show that the Eppelsheim and D. laietanus femora fit different hindlimb morphologies with regard to relative length and relative head/neck size, with Paidopithex significantly differing from Dryopithecus, but more closely resembling Pliopithecus. Paidopithex also differs from Dryopithecus in other important aspects, such as its lower neck/shaft angle, lack of elevation of the femoral head above the greater trochanter, more posteriorly oriented lesser trochanter, and proximal shaft diameter thicker anteroposteriorly than mediolaterally. In these features, Paidopithex most closely resembles Pliopithecus in spite of differences in body mass (ca. 22 kg vs. ca. 10 kg, respectively). These features suggest that Paidopithex used a primitive locomotor pattern associated with arboreal quadrupedalism, instead of the more derived pattern displayed by Dryopithecus. Currently available evidence confirms that the attribution of Paidopithex to Dryopithecus can be rejected. Paidopithex could be a large and otherwise unknown pliopithecid, but the possibility cannot be ruled out that it represents a third kind of catarrhine.