Chronic administration of EGb 761 modulates synaptic and mitochondrial plasticity in adult vitamin E-deficient rats.

A computer-assisted morphometric study has been carried out on synaptic junctions and synaptic mitochondria in the dentate gyrus supragranular layer of vitamin E-deficient rats undergone chronic administration of the extract EGb 761 from Ginkgo biloba leaves (100 mg/kg body weight, daily, from 4 to 7 months of age). Control animals were fed with the vitamin E-deficient diet from 1 to 7 months of age. Numeric density (Nv), surface density (Sv) and average size of the synaptic junctions (S), mitochondrial numeric density (Nvm), volume density (Vv) and average volume (V) were the measured parameters. In EGb 761-treated animals, Nv was significantly increased and S significantly decreased, while Sv was unchanged. EGb 761 administration resulted in an increased percentage of synapses of smaller size. In EGb 761-treated rats, Nvm significantly increased and V significantly decreased, while no significant difference of Vv was found. The population of synaptic mitochondria in EGb 761 -treated animals was composed of a higher number of smaller organelles. The measured parameters report on the structural dynamics of synapses and mitochondria, thus our findings support that EGb 761 administration is able to improve the physiological adaptive capacities of the investigated structures by a positive modulation of their morphofunctional features.     

A survey of ontogeny pericarp features as contribution to the infratribal characterization of Myrteae (Myrtaceae)

With the aim of correlating the pericarp structure with current phylogenies of Myrteae, this study describes the ontogeny in five species included in five out of the six South American clades of the tribe. In these taxa, the outer and inner ovarian epidermis gives rise to the exocarp and the endocarp, respectively, both with 1 layer. In the mesocarp, derived from the ovarian mesophyll, secretory cavities are arranged into a circle just below the exocarp and near the endocarp in Campomanesia adamantium; only below the exocarp in Eugenia pitanga and Myrcia multiflora; more internally in Myrciaria cuspidata, and below the exocarp and throughout the mesophyll in Myrceugenia alpigena. The promising traits for phylogenetic studies in the group include: direction of elongation of pericarp layers, regions that develop most in relation to the circle of larger vascular bundles, differentiation of spongy and sclerenchymatous tissues and position of secretory cavities.     

Multiple introductions and gene flow in subtropical South American populations of the fireweed,Senecio madagascariensis(Asteraceae)

Non-indigenous plants exhibit different attributes that make them aggressive competitors with indigenous plants and serious threats to biodiversity.Senecio madagascariensis (fireweed, Asteraceae), a native from southern Africa, is a strong competitor in agricultural activities and has toxic alkaloids that may result in high cattle mortality. In Brazil, this weed was collected for the first time in 1995 and has since spread quickly throughout the Pampas region. To better understand the invasion of the fireweed in South America, we used a genetic characterization with internal transcribed spacer (ITS) and microsatellite markers. Based on the ITS data, the southern Brazil populations of S. madagascariensis shared genetic homology with samples taken from the Hawaiian Islands and South Africa. Microsatellite analysis showed the genetic diversity split in two clusters, perhaps intimating the independent introduction of each species into South America. Although fireweed was introduced recently in southern Brazil, the considerable levels of genetic diversity, gene flow, and inbreeding may indicate success in the species establishment in this environment.     

Site-directed mutagenesis of two aromatic residues lining the active site pocket of the yeast Ltp1

We mutated Trp(134) and Tyr(135) of the yeast LMW-PTP to explore their catalytic roles, demonstrating that the mutations of Trp(134) to Tyr or Ala, and Tyr(135) to Ala, all interfere with the formation of the phosphorylenzyme intermediate, a phenomenon that can be seen by the decrease in the kinetic constant of the chemical step (k(3)). Furthermore, we noted that the Trp(134) to Ala mutation causes a dramatic drop in k(cat)/K(m) and a slight enhancement of the dissociation constant K(s). The conservative mutant W134Y shows a k(cat)/K(m) very close to that of wild type, probably compensating the two-fold decrease of k(3) with an increase in substrate affinity. The Y135A mutation enhances the substrate affinity, but reduces the enzyme phosphorylation rate. The replacement of Trp(134) with alanine interferes with the partition between phosphorylenzyme hydrolysis and phosphotransfer from the phosphorylenzyme to glycerol and abolish the enzyme activation by adenine. Finally, we found that mutation of Trp(134) to Ala causes a dramatic change in the pH-rate profile that becomes similar to that of the D132A mutant, suggesting that an aromatic residue in position 134 is necessary to assist the proper positioning of the proton donor in the transition state of the chemical step.     

Interleukin 1 in oviductal tissues of viviparous, oviparous, and ovuliparous species of amphibians

In previous reports, we have shown that interleukin 1 (IL1), a cytokine associated with implantation in mice, is also expressed in reproductive tissues of viviparous squamate reptiles and cartilaginous fishes. In the present study, we investigated the expression of IL1B and its functional membrane receptor type I (IL1R1) in amphibians, a class of vertebrates that is characterized by different reproductive modes, including internal and external fertilization. In particular, we investigated the oviductal tissues of the aplacental viviparous Salamandra lanzai, the oviparous Triturus carnifex, and the ovuliparous Bufo bufo. In immunohistochemistry with anti-human IL1B and IL1R1 polyclonal antibodies we found that in S. lanzai, most cells in the uterine mucosa were immunoreactive for IL1B and IL1R1. In T. carnifex, IL1B and IL1R1 were present in ciliated luminal cells, and there was evidence of IL1B in glandular cells. In B. bufo, the expression of IL1B and IL1R1 was limited to the apical cytoplasm of the ciliated oviductal cells. Western blot analysis showed that a putative mature form of IL1B, similar to that seen in mammals, was present in the oviductal tissues of S. lanzai, whereas different forms, which probably correspond to an inactive pro-IL1B protein, were found in T. carnifex and B. bufo. A band that corresponded to the predicted 80-kDa human IL1R1 was found in S. lanzai and T. carnifex. Although the present study shows that IL1B and IL1R1 expression occurs in all reproductive modes, the differential expression patterns noted between ovuliparity and oviparity and viviparity may reflect the different roles of IL1 in the various reproductive modes.