Metallothioneins and energy budget indices in cadmium and copper exposed spiders Agelena labyrinthica in relation to their developmental stage, gender and origin

The aim of our studies was to explain the role of metallothioneins (MTs) in the neutralization of excessive amounts of metals (essential: copper (Cu) and toxic: cadmium (Cd)) and to describe the energy status in metal-exposed spiders Agelena labyrinthica in relation to its developmental stage, gender and origin. Juvenile, female and male spiders were collected from three variously polluted habitats, transferred to the laboratory and exposed to the metals in their diet. Cu and Cd accumulation in the body and exuviae, bioaccumulation factor, percentage of metallothionein positive cells, MT concentration, percentage of cells with depolarized mitochondria, ATP concentration and ADP/ATP ratio were measured and calculated. Cu appeared to be regulated and its excess is eliminated via, among others, the molting process, while Cd was rather accumulated by the spiders. The level of MTs increased significantly mainly in females exposed to both metals, irrespectively of the pollution degree of their site of origin, indicating a defensive role of the proteins. In general, even if both the MT level and the energy status indices were positively correlated with Cd and Cu concentrations in the spider body, the energy status of A. labyrinthica did not seem disturbed.     

Ku70 and Rad51 vary in their importance for the repair of doxorubicin- versus etoposide-induced DNA damage

For DNA targeting anticancer drugs, cellular DNA repair mechanisms may cause resistance and hamper the therapeutic outcome. DNA damage induced by topoisomerase IIα inhibitors like etoposide and anthracyclines, which are a mainstay of cancer therapy, is also repaired in many cell types, but the impact and precise mechanisms of this repair are still obscure. To investigate the DNA damage response of human adenocarcinoma HT29-cells to doxorubicin and to compare the involvement of Ku70 and Rad51 in the repair of doxorubicin- versus etoposide-induced DNA damage, we assessed cell cycle distribution and cell death, DNA damage, proteins relevant for repair by homologous recombination and non-homologous end-joining, and clonogenicity following exposure to doxorubicin at clinically achievable concentrations. Also, we assessed changes in the repair kinetics after siRNA-mediated attenuation of Ku70 or Rad51 expression. We found that exposure to doxorubicin for 24 h induced a substantial amount of DNA damage that was largely repaired when doxorubicin was removed and the cells were maintained in drug-free medium. Nevertheless, a pronounced G₂/M arrest occurred at times when repair was maximal. This was followed by a distinct increase in cell death and loss of clonogenicity. In this regard, responses to doxorubicin and etoposide were similar. However, distinct differences in the repair process following doxorubicin versus etoposide were seen in concentration dependency, time-course and requirement of Ku70 and Rad51 proteins. In spite of the shared molecular target of doxorubicin and etoposide, DNA lesions induced by these compounds are repaired differently.     

Identification and characterization of a unique,zinc-containing transport ATPase essential for natural transformation in <Emphasis Type="Italic">Thermus thermophilus</Emphasis> HB27

Thermus thermophilus is a model strain to unravel the molecular basis of horizontal gene transfer in hot environments. Previous genetic studies led to the identification of a macromolecular transport machinery mediating DNA uptake in an energy-dependent manner. Here, we have addressed how the transporter is energized. Inspection of the genome sequence revealed four putative transport (AAA) ATPases but only the deletion of one, PilF, led to a transformation defect. PilF is similar to transport ATPases of type IV and type II secretions systems but has a unique N-terminal sequence that carries a triplicated GSPII domain. To characterize PilF biochemically it was produced in Escherichia coli and purified. The recombinant protein displayed NTPase activity with a preference for ATP. Gel filtration analyses combined with dynamic light scattering demonstrated that PilF is monodispersed in solution and forms a complex of 590 ± 30 kDa, indicating a homooligomer of six subunits. It contains a tetracysteine motif, previously shown to bind Zn²⁺ in related NTPases. Using atomic absorption spectroscopy, indeed Zn²⁺ was detected in the enzyme, but in contrast to all known zinc-binding traffic NTPases only one zinc atom was bound to the hexamer. Deletion of the four cysteine residues led to a loss of Zn²⁺. Nevertheless, the mutant protein retained ATPase activity and hexameric complex formation.     

Modelling the protective efficacy of alternative delivery schedules for intermittent preventive treatment of malaria in infants and children

Background

Intermittent preventive treatment in infants (IPTi) with sulfadoxine-pyrimethamine (SP) is recommended by WHO where malaria incidence in infancy is high and SP resistance is low. The current delivery strategy is via routine Expanded Program on Immunisation contacts during infancy (EPI-IPTi). However, improvements to this approach may be possible where malaria transmission is seasonal, or where the malaria burden lies mainly outside infancy.

Methods and Findings

A mathematical model was developed to estimate the protective efficacy (PE) of IPT against clinical malaria in children aged 2-24 months, using entomological and epidemiological data from an EPI-IPTi trial in Navrongo, Ghana to parameterise the model. The protection achieved by seasonally-targeted IPT in infants (sIPTi), seasonal IPT in children (sIPTc), and by case-management with long-acting artemisinin combination therapies (LA-ACTs) was predicted for Navrongo and for sites with different transmission intensity and seasonality. In Navrongo, the predicted PE of sIPTi was 26% by 24 months of age, compared to 16% with EPI-IPTi. sIPTc given to all children under 2 years would provide PE of 52% by 24 months of age. Seasonally-targeted IPT retained its advantages in a range of transmission patterns. Under certain circumstances, LA-ACTs for case-management may provide similar protection to EPI-IPTi. However, EPI-IPTi or sIPT combined with LA-ACTs would be substantially more protective than either strategy used alone.

Conclusion

Delivery of IPT to infants via the EPI is sub-optimal because individuals are not protected by IPT at the time of highest malaria risk, and because older children are not protected. Alternative delivery strategies to the EPI are needed where transmission varies seasonally or the malaria burden extends beyond infancy. Long-acting ACTs may also make important reductions in malaria incidence. However, delivery systems must be developed to ensure that both forms of chemoprevention reach the individuals who are most exposed to malaria.     

Morphological and functional alterations in adult boar epididymis: Effects of prenatal and postnatal administration of flutamide

Background  

The dynamic cross-talk between epididymal cells is hormonally regulated and, in part, through direct cell-to-cell interactions. To date, no information is available regarding possible impact of anti-androgens on the proteins involved in the gap junctional communication within the boar epididymis. Thus, a question arised whether prenatal or postnatal exposure to an anti-androgen flutamide alters the expression of gap junction protein - connexin43 (Cx43) and androgen receptor (AR) expression in the caput, corpus and cauda epididymis and leads to delayed effects on morphology and function of adult pig epididymis.     

Effect of S-methylmethionine on the photosynthesis in maize at different chilling temperatures

The effect of the natural compound S-methylmethionine (SMM) on the functioning of the photosynthetic apparatus, the efficiency of photosynthesis and the synthesis of stress-induced phenoloids and anthocyanins involved in defence was investigated in young maize plants exposed to moderate and severe chilling stress. Damage to PSII was observed as a reduction in the value of variable fluorescence (Fv/Fm) which could be detected even after few hours of mild chilling stress. At temperatures below 10°C, the reduction in Fv/Fm was more pronounced. Changes in the value of net photosynthesis exhibited a similar tendency. SMM has a moderating effect on this reduction and its protective effect was more pronounced under long-lasting chilling stress and at the lowest temperatures. Monitoring of fluorescence intensities and ratios correlated with the levels of stress defence compounds. The fluorescence intensities were found to increase over the course of chilling stress in response to SMM, with the highest values being recorded in plants exposed to the longest period of stress. A similar tendency was observed for the quantity of anthocyanins. The results confirm the complex role of SMM, which is manifested both in preserving the ability of the photosynthetic apparatus to function and in stimulating the synthesis of metabolites involved in stress defence.     

Vision First? The Development of Primary Visual Cortical Networks Is More Rapid Than the Development of Primary Motor Networks in Humans

The development of cortical functions and the capacity of the mature brain to learn are largely determined by the establishment and maintenance of neocortical networks. Here we address the human development of long-range connectivity in primary visual and motor cortices, using well-established behavioral measures--a Contour Integration test and a Finger-tapping task--that have been shown to be related to these specific primary areas, and the long-range neural connectivity within those. Possible confounding factors, such as different task requirements (complexity, cognitive load) are eliminated by using these tasks in a learning paradigm. We find that there is a temporal lag between the developmental timing of primary sensory vs. motor areas with an advantage of visual development; we also confirm that human development is very slow in both cases, and that there is a retained capacity for practice induced plastic changes in adults. This pattern of results seems to point to human-specific development of the "canonical circuits" of primary sensory and motor cortices, probably reflecting the ecological requirements of human life.