Anti-fibrillogenic and fibril destabilizing effects of metal ions on cystatin fibrils

Metals such as Cu²⁺, Fe³⁺, and Zn²⁺ are major contributors to the biology of a brain in stages of health, aging, and disease because of their unique effects on both protein structures (misfolding) and oxidative stress. The relationship between metal ions and neurodegenerative diseases is very complicated. Our study highlights how metal ions influence amyloid formation at low pH and on preformed amyloid fibrils. By using thioflavin T assay, ANS fluorescence, Congo red assay, circular dichroism, and microscopy to elucidate the effects of Cu²⁺, Fe³⁺, and Zn²⁺ on goat brain cystatin (GBC) aggregation at low pH. Results showed that Cu²⁺ and Fe³⁺ inhibit fibril formation of GBC by promoting amorphous aggregates. However, Zn²⁺ exclusively promotes fibril formation at low pH, leading to the formation of more ordered aggregates. Furthermore, the combined results of these complementary methods also suggested that Cu²⁺ and Fe³⁺ destabilize the β-sheet secondary structure of preformed amyloid fibrils of GBC.     

Pre‐zygotic reproductive isolation between two synchronopatric Opuntia (Cactaceae) species in the Brazilian Chaco

• Opuntia (Cactaceae) is known for high rates of hybridization and ploidisation, resulting in the formation of new species. The occurrence of two sympatric and closely related species of Opuntia, O. elata and O. retrorsa, in Brazilian Chaco enabled us to test the hypothesis that pre‐zygotic reproductive isolation mechanisms operate in both species.
• We monitored the flowering period, as well as floral biology, and compared the morphological variation of floral structures through measurements, performed intra‐ and interspecific cross‐pollination tests, and recorded the guild of floral visitors and pollinators.
• Flowering was seasonal and highly synchronous. Floral biology exhibits similar strategies, and although floral morphology differs significantly in many of the compared structures, such morphological variation does not result in the selection of exclusive pollinators. Floral visitors and pollinators are oligolectic bees shared by both species. Opuntia elata and O. retrorsa are self‐compatible. While interspecific cross‐pollination (bidirectional) resulted in germination, the pollen tube did not penetrate the stigma.
• Opuntia elata and O. retrorsa are closely related; however, they are isolated and do not hybridise in Brazilian Chaco. We found that both have weak pre‐pollination barriers, but that they are strongly isolated by pollen–pistil incompatibility, i.e. post‐pollination barrier.

     

Epigenetic Regulator CoREST Controls Social Behavior in Ants

1. Download : Download high-res image (203KB)
2. Download : Download full-size image

     

Neuronal calcium signaling via store-operated channels in health and disease

Store-operated calcium entry (SOCE) is the flow of calcium ions (Ca²⁺) into cells in response to the depletion of intracellular Ca²⁺ stores that reside predominantly in the endoplasmic reticulum (ER). The role of SOCE has been relatively well understood for non-excitable cells. It is mediated mostly by the ER Ca²⁺ sensor STIM1 and plasma membrane Ca²⁺ channel Orai1 and serves to sustain Ca²⁺ signaling and refill ER Ca²⁺ stores. In contrast, because of the complexity of Ca²⁺ influx mechanisms that are present in excitable cells, our knowledge about the function of neuronal SOCE (nSOCE) is still nascent. This review summarizes the available data on the molecular components of nSOCE and their relevance to neuronal signaling. We also present evidence of disturbances of nSOCE in neurodegenerative diseases (namely Alzheimer’s disease, Huntington’s disease, and Parkinson’s disease) and traumatic brain injury. The emerging important role of nSOCE in neuronal physiology and pathology makes it a possible clinical target.     

Can the problem of hybridization in threatened species be evaluated using a fieldwork research? A case study in snapdragons

Hybridization, natural or artificial, is considered disadvantageous for species biodiversity when it threatens the population integrity of endangered species. Frequently, studies investigating whether hybridization poses a legitimate risk to rare species are based on genetic data obtained in molecular biology laboratories. In this study, we used field research to approach the problem that hybridization could cause for the viability of a population of a rare species and to be able to propose the most appropriate initial conservation strategy. Specifically, using the model genus Antirrhinum, the reproductive barriers between the rare A. pulverulentum and its common congener A. litigiosum have been analysed under the reproductive isolation index (RI). A. pulverulentum had a high value of total RI, indicating that there are barriers to gene flow from A. litigiosum towards this species, and also had a high value for the intrinsic RI, reflecting a low inherent capacity for production of hybrid plants; in addition, the possibility of successful backcrosses between this species with hybrids produced from A. litigiosum ovules were low, given the high intrinsic RI of A. litigiosum. These data indicate the current existence of strong and permanent barriers to hybridization between the two species, suggesting that hybridization does not seem to be a serious problem for the conservation of A. pulverulentum in the studied population, nor for the near future. This study shows how the RI index can provide useful information for conservation purposes and proposes different management recommendations.     

Ensembles of endothelial and mural cells promote angiogenesis in prenatal human brain

1. Download : Download high-res image (311KB)
2. Download : Download full-size image

     

Immunohistochemical Detection of Phenol Sulfotransferase-Containing Neurons in Human Brain

Using antibodies raised against human platelet phenol sulfotransferase (PST), immunohistochemical studies were performed to determine the cellular localization of PST in several areas of human brain. In the hippocampus PST immunoreactivity was localized in both the pyramidal and nonpyramidal neurons and was in greatest abundance in the CA2 and CA3 areas. In the striatum the immunoreactivity was most predominant in the large neurons of the globus pallidus and in the medulla the staining was scattered throughout the neurons of the raphe nucleus and the reticular formation. The selective presence of PST in the neurons of the CNS raises the issue as to the role of this enzyme in sulfating neurotransmitters because PST has been shown to be capable of conjugating a variety of neurotransmitters including the catecholamines as well as the tyrosine moiety of a number of small peptides such as enkephalin and cholecystokinin.