Effect of Chronic Variate Stress on Thiobarbituric-Acid Reactive Species and on Total Radical-Trapping Potential in Distinct Regions of Rat Brain

It has been suggested that oxidative stress is involved in aging and neuropathologic disorders. In addition, chronic stress and high corticosterone levels are suggested to induce neuronal death. The aim of this study is to verify the effect of chronic variate stress on lipoperoxidation and on the total radical-trapping potential (TRAP) in hippocampus, hypothalamus and cerebral cortex. Adult male Wistar rats were submitted to different stressors during 40 days. Lipid peroxide levels were assessed by the thiobarbituric acid reactive species (TBARS) reaction, and TRAP was measured by the decrease in luminescence using the 2-2-azo-bis(2-amidinopropane)-luminol system. The results showed that in cerebral cortex homogenates chronic stress induces an increase in oxidative stress. In hypothalamus a decreased lipoperoxidation was observed, however TRAP showed no difference. In hippocampus no difference was observed. We concluded that prolonged stress induces oxidative stress which varies selectively with the brain region.     

Chemotaxonomic study on Thymus villosus from Portugal

The composition of the essential oils of four populations of Thymus villosus subsp. lusitanicus (Boiss.) Coutinho from Portugal was investigated by GC and GC-MS. To study the chemical polymorphism the results obtained from GC analyses of the volatile oils from individual plants from four populations were submited to Principal Component and Cluster analyses. A comparision with the essential oil of T. villosus subsp. villosus, previously studied by us was done. Important differences with regard to the major constituents in these two taxa were found. Linalool, geranyl acetate, geraniol and terpinen-4-ol were the main components of the essential oils of T. villosus subsp. lusitanicus, whereas in the oil of T. villosus subsp. villosus p-cymene, myrcene and alpha-terpineol were the major ones. Although, both taxa showed chemical polymorphism, different types of essential oils were characterized in each one: linalool; linalool/ terpinen-4-ol/trans-sabinene hydrate; linalool/1,8-cineole; geranyl acetate/geraniol; geranyl acetate/geraniol/1,8-cineole in T. villosus subsp. lusitanicus and p-cymene/camphor/linalool; p-cymene/borneol; linalool/geraniol/geranyl acetate; alpha-terpineol/camphor/myrcene in T. villosus subsp. villosus. Thus, the two subspecies of T. villosus can be easely differenciated by the composition of their essential oils.     

The EF-Hand Ca2+ Binding Protein MICU Choreographs Mitochondrial Ca2+ Dynamics in Arabidopsis

Plant organelle function must constantly adjust to environmental conditions, which requires dynamic coordination. Ca²⁺ signaling may play a central role in this process. Free Ca²⁺ dynamics are tightly regulated and differ markedly between the cytosol, plastid stroma, and mitochondrial matrix. The mechanistic basis of compartment-specific Ca²⁺ dynamics is poorly understood. Here, we studied the function of At-MICU, an EF-hand protein of Arabidopsis thaliana with homology to constituents of the mitochondrial Ca²⁺ uniporter machinery in mammals. MICU binds Ca²⁺ and localizes to the mitochondria in Arabidopsis. In vivo imaging of roots expressing a genetically encoded Ca²⁺ sensor in the mitochondrial matrix revealed that lack of MICU increased resting concentrations of free Ca²⁺ in the matrix. Furthermore, Ca²⁺ elevations triggered by auxin and extracellular ATP occurred more rapidly and reached higher maximal concentrations in the mitochondria of micu mutants, whereas cytosolic Ca²⁺ signatures remained unchanged. These findings support the idea that a conserved uniporter system, with composition and regulation distinct from the mammalian machinery, mediates mitochondrial Ca²⁺ uptake in plants under in vivo conditions. They further suggest that MICU acts as a throttle that controls Ca²⁺ uptake by moderating influx, thereby shaping Ca²⁺ signatures in the matrix and preserving mitochondrial homeostasis. Our results open the door to genetic dissection of mitochondrial Ca²⁺ signaling in plants.     

Helminth parasite diversity discloses age and sex differences in the foraging behaviour of southern lapwings (Vanellus chilensis)

Parasites with heteroxen cycles are important sources of information on the trophic relations of hosts. This is particularly instructive for species whose age‐based or sex‐based differences are hardly detected by behavioural observations. Here, we describe the helminth community of the omnivorous southern lapwing (Vanellus chilensis) and evaluate whether it is affected by the host's sex, age and body size. The species is sexually monomorphic in body length, but males are slightly heavier than females. We analysed 112 individuals collected in Curitiba, Brazil, in March 2010. All hosts were parasitized. The helminth community was composed of 10 species (the digeneans Leucochloridium parcum and Athesmia sp., the cestode Infula macrophallus, the acantocephalans Plagiorhynchus sp., Centrorhynchus sp., Mediorhynchus sp., and an unidentified Gigantorhynchida, and the nematodes Heterakis psophiae, Dispharynx nasuta and an unidentified Capillariidae), seven of which were novel reports for this host species. Prevalence ranged from <1% to 99%. Whereas I. macrophallus was the most prevalent species, D. nasuta showed the highest mean intensity and abundance of infection. The former was found in most hosts as single male–female pairs, suggesting the occurrence of intrasexual competition. The infracommunities of juvenile birds showed a higher parasite species richness than those of adult males and females, suggesting the exploitation of a wider array of prey. However, the three classes harboured seven parasite species. Differences in parasite diversity (lower in juveniles, intermediate in adult males and higher in adult females) reflect the evenness in the distribution of parasite specimens among taxa in each age–sex class and are compatible with differences in their foraging strategy. Finally, we conclude based on the cycles of the heteroxen species that southern lapwings preyed upon molluscs, coleopterans, woodlice and earthworms.     

Mutations in PNKP Cause Recessive Ataxia with Oculomotor Apraxia Type 4

Hereditary autosomal-recessive cerebellar ataxias are a genetically and clinically heterogeneous group of disorders. We used homozygosity mapping and exome sequencing to study a cohort of nine Portuguese families who were identified during a nationwide, population-based, systematic survey as displaying a consistent phenotype of recessive ataxia with oculomotor apraxia (AOA). The integration of data from these analyses led to the identification of the same homozygous PNKP (polynucleotide kinase 3′-phosphatase) mutation, c.1123G>T (p.Gly375Trp), in three of the studied families. When analyzing this particular gene in the exome sequencing data from the remaining cohort, we identified homozygous or compound-heterozygous mutations in five other families. PNKP is a dual-function enzyme with a key role in different pathways of DNA-damage repair. Mutations in this gene have previously been associated with an autosomal-recessive syndrome characterized by microcephaly; early-onset, intractable seizures; and developmental delay (MCSZ). The finding of PNKP mutations associated with recessive AOA extends the phenotype associated with this gene and identifies a fourth locus that causes AOA. These data confirm that MCSZ and some forms of ataxia share etiological features, most likely reflecting the role of PNKP in DNA-repair mechanisms.     

DNA damage in the kidney tissue cells of the fish Rhamdia quelen after trophic contamination with aluminum sulfate

Even though aluminum is the third most common element present in the earth''s crust, information regarding its toxicity remains scarce. It is known that in certain cases, aluminum is neurotoxic, but its effect in other tissues is unknown. The aim of this work was to analyze the genotoxic potential of aluminum sulfate in kidney tissue of the fish Rhamdia quelen after trophic contamination for 60 days. Sixty four fish were subdivided into the following groups: negative control, 5 mg, 50 mg and 500 mg of aluminum sulfate per kg of fish. Samples of the posterior kidney were taken and prepared to obtain mitotic metaphase, as well as the comet assay. The three types of chromosomal abnormalities (CA) found were categorized as chromatid breaks, decondensation of telomeric region, and early separation of sister chromatids. The tests for CA showed that the 5 mg/kg and 50 mg/kg doses of aluminum sulfate had genotoxic potential. Under these treatments, early separation of the sister chromatids was observed more frequently and decondensation of the telomeric region tended to increase in frequency. We suggest that structural changes in the proteins involved in DNA compaction may have led to the decondensation of the telomeric region, making the DNA susceptible to breaks. Moreover, early separation of the sister chromatids may have occurred due to changes in the mobility of chromosomes or proteins that keep the sister chromatids together. The comet assay confirmed the genotoxicity of aluminum sulfate in the kidney tissue of Rhamdia quelen at the three doses of exposure.