Phytogeographic implications of fossil endocarps of Menispermaceae from the Paleocene of Colombia

? Premise of the study: Fossil leaves of Menispermaceae were previously described from the Paleocene of Colombia. Because of strong homoplasy of leaf characters, the fossils could not be placed more specifically within recognized clades, and additional data were needed to specify intrafamilial and paleogeographic relationships during the Paleocene. ? Methods: Fossil endocarps of Menispermaceae were collected from the Cerrejón Formation, the recently discovered Bogotá flora, and Wyoming (～60 Ma). We surveyed the endocarp morphology of almost all extant genera, conducted character optimization, a molecular scaffold analysis, and critically reviewed the related fossil genera. ? Key results: Parallel syndromes of fruit characters have appeared in unrelated clades of the family according to current phylogenetic reconstructions. However, mapping selected endocarp characters across those clades that contain horseshoe-shaped endocarps facilitates identification and phylogenetic assessment of the fossils. Three fossil species are recognized. One of them belongs to the extant genus Stephania, which today grows only in Africa and Australasia. Palaeoluna gen. nov. is placed within the pantropical clade composed of extant Stephania, Cissampelos, and Cyclea; this morphogenus is also recognized from the Paleocene of Wyoming. Menispina gen. nov. shows similarity with several unrelated clades. ? Conclusions: The new fossils from Colombia reveal a complex paleobiogeographic history of the recognized clades within Menispermaceae, suggesting a more active exchange among neotropical, paleotropical, North American, and European paleoforests than previously recognized. In addition, the new fossils indicate that neotropical forests were an important biome for the radiation and dispersal of derived lineages in Menispermaceae after the Cretaceous-Paleogene boundary.     

Use of divalent metal ions in the DNA cleavage reaction of topoisomerase IV

It has long been known that type II topoisomerases require divalent metal ions in order to cleave DNA. Kinetic, mutagenesis and structural studies indicate that the eukaryotic enzymes utilize a novel variant of the canonical two-metal-ion mechanism to promote DNA scission. However, the role of metal ions in the cleavage reaction mediated by bacterial type II enzymes has been controversial. Therefore, to resolve this critical issue, this study characterized the DNA cleavage reaction of Escherichia coli topoisomerase IV. We utilized a series of divalent metal ions with varying thiophilicities in conjunction with oligonucleotides that replaced bridging and non-bridging oxygen atoms at (and near) the scissile bond with sulfur atoms. DNA scission was enhanced when thiophilic metal ions were used with substrates that contained bridging sulfur atoms. In addition, the metal-ion dependence of DNA cleavage was sigmoidal in nature, and rates and levels of DNA cleavage increased when metal ion mixtures were used in reactions. Based on these findings, we propose that topoisomerase IV cleaves DNA using a two-metal-ion mechanism in which one of the metal ions makes a critical interaction with the 3'-bridging atom of the scissile phosphate and facilitates DNA scission by the bacterial type II enzyme.     

Rostrocaudal dynamics of CSF biomarkers

The rostrocaudal gradient (RCG) of markers present in cerebrospinal fluid (CSF) has not been studied adequately due to lack of appropriate control populations and ethical restrictions. The aim of this study is to understand the rostrocaudal gradient of CSF biomarkers. We contacted a study comparing CSF levels of seven biomarkers from cisternal (rostral) and lumbar (caudal) CSF obtained from patients with trigeminal neuralgia and tension-type headache. The RCGs of CSF/serum albumin ratio, 8-isoprostane. GFAP, total tau and beta amyloid protein were higher than one. The RCGs of lactate, VEGF and the heavy chain of neurofilament protein were lower than one. The study provides new values for several commonly examined markers of cisternal CSF. Knowledge of the RCG gradient of different CSF markers is important in interpreting studies reporting ventricular CSF values.     

The effects of phenolic components of tea on the production of pro- and anti-inflammatory cytokines by human leukocytes in vitro

Epidemiological evidence suggests protective effects of dietary flavonoids against cardiovascular disease. Tea provides a major source of dietary flavonoids in many countries and its polyphenolic components have well-recognised antioxidant properties. However, scavenging of free radicals may not be the sole mechanism by which tea-derived polyphenols exert their protective effects. This study investigates the effects of four major tea-derived catechins and a black tea extract on the production of pro- and anti-inflammatory cytokines by human leukocytes in vitro. Epicatechin gallate, epigallocatechin and epigallocatechin gallate decreased the production of interleukin 1beta and enhanced the production of interleukin 10, but had no effect on the production of interleukin 6 or tumour necrosis factor-alpha. Although these effects suggest anti-inflammatory properties of the tea-derived catechins, they were observed at concentrations which were unlikely to be achievable in plasma in vivo and are therefore unlikely to contribute to the protective effects of tea-derived flavonoids in inflammatory diseases.     

Single-molecule force spectroscopy: optical tweezers, magnetic tweezers and atomic force microscopy

Single-molecule force spectroscopy has emerged as a powerful tool to investigate the forces and motions associated with biological molecules and enzymatic activity. The most common force spectroscopy techniques are optical tweezers, magnetic tweezers and atomic force microscopy. Here we describe these techniques and illustrate them with examples highlighting current capabilities and limitations.     

Sirtuin 1-mediated Effects of Exercise and Resveratrol on Mitochondrial Biogenesis

The purpose of this study was to evaluate the role of sirtuin 1 (SirT1) in exercise- and resveratrol (RSV)-induced skeletal muscle mitochondrial biogenesis. Using muscle-specific SirT1-deficient (KO) mice and a cell culture model of differentiated myotubes, we compared the treatment of resveratrol, an activator of SirT1, with that of exercise in inducing mitochondrial biogenesis. These experiments demonstrated that SirT1 plays a modest role in maintaining basal mitochondrial content and a larger role in preserving mitochondrial function. Furthermore, voluntary exercise and RSV treatment induced mitochondrial biogenesis in a SirT1-independent manner. However, when RSV and exercise were combined, a SirT1-dependent synergistic effect was evident, leading to enhanced translocation of PGC-1α and SirT1 to the nucleus and stimulation of mitochondrial biogenesis. Thus, the magnitude of the effect of RSV on muscle mitochondrial biogenesis is reliant on SirT1, as well as the cellular environment, such as that produced by repeated bouts of exercise.     

Natural occurrence of deoxynivalenol, 3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol,nivalenol, 4,7-dideoxynivalenol,and zearalenone in polish wheat

Three wheat samples collected in 1987 in Central Poland and naturally infected withFusarium spp were analyzed for the presence ofFusarium spp andFusarium toxins. Heads were separated into three fractions: kernels with visibleFusarium damage, healthy looking kernels, and chaff + rachis. The samples contained deoxynivalenol (2.0 – 40.0μg/g), nivalenol (O.O1μg/g), 4,7-dideoxynivalenol (0.10 – 0.15μg/g). 15-acetyldeoxynivalenol (0.10–2.00 μg/g), 3-acetyldeoxynivalenol (O/1Oμg/g), and zearalenone (0.01–2.00μg/g). This is the first report about 15 - acetyldeoxynivalenol in European wheat and the co-occurrence of 3 - acetyldeoxynivalenol and 15-acetyldeoxynivalenol in the same sample of contaminated cereals.