Investigating the mechanisms of photosynthetic proteins using continuum electrostatics

Computational methods based on continuum electrostatics are widely used in theoretical biochemistry to analyze the function of proteins. Continuum electrostatic methods in combination with quantum chemical and molecular mechanical methods can help to analyze even very complex biochemical systems. In this article, applications of these methods to proteins involved in photosynthesis are reviewed. After giving a short introduction to the basic concepts of the continuum electrostatic model based on the Poisson-Boltzmann equation, we describe the application of this approach to the docking of electron transfer proteins, to the comparison of isofunctional proteins, to the tuning of absorption spectra, to the analysis of the coupling of electron and proton transfer, to the analysis of the effect of membrane potentials on the energetics of membrane proteins, and to the kinetics of charge transfer reactions. Simulations as those reviewed in this article help to analyze molecular mechanisms on the basis of the structure of the protein, guide new experiments, and provide a better and deeper understanding of protein functions.     

Gender-related differences in elite gymnasts: the female athlete triad.

High-intensity training can alter the normal pattern of pubertal development in elite gymnasts. We investigated sex hormones, the ob gene product leptin, body composition, nutrition, and eating habits in female and male elite gymnasts from national cadres to elucidate gender-related differences. Serum leptin levels were decreased, particularly in pubertal girls, and did not show the normal developmental pattern. After leptin levels were transformed into standard deviation scores, mainly pubertal female gymnasts had significantly lower values than normal controls of the same gender, pubertal stage, and body mass index. The percentage of body fat was reduced compared with a normal age-matched population in both genders but to a higher degree in female gymnasts. When leptin standard deviation scores were based on percent body fat instead of body mass index, mean values were still significantly decreased compared with those of normal controls: -1.05 in girls (P < 0.001) and -0.60 in boys (P = 0.025). In both genders, total energy consumption and nutritional intake were insufficient, although to a lesser extent in male gymnasts. Pubertal development is influenced to a different degree in female and male elite gymnasts. In contrast to their male counterparts, high-intensity training takes place during the sensitive phase of pubertal maturation in female gymnasts. Whereas the girls displayed low estrogen levels, hypoleptinemia, reduced body fat mass, insufficient caloric intake, and retarded menarche, the pubertal development of male gymnasts remained almost unaltered.     

The conditioned medium from osteo‐differentiating human mesenchymal stem cells affects the viability of triple negative MDA‐MB231 breast cancer cells

This study aimed to investigate the effect of conditioned media (CM) from osteo‐differentiating and adipo‐differentiating human mesenchymal stem cells (MSCs) isolated from lipoaspirates of healthy female donors on the viability of triple‐negative breast cancer cells MDA‐MB231. The CM of undifferentiated and differentiating MSCs were collected after 7, 14, 21 and 28 days of culture. The effects of MSC CM on cell proliferation were assessed using an 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay after 24 h. The effects of osteo‐differentiating cell CM on apoptotic promotion, cell cycle impairment, mitochondrial transmembrane potential dissipation, production of reactive oxygen species and autophagosome accumulation were analysed by flow cytometry and Western blot. MTT assay showed that only CM collected from osteo‐induced cells at day 28 (d28O‐CM) reduced tumour cell viability. Treatment with d28O‐CM restrained cell cycle progression through G₂ phase, elicited a caspase‐8‐driven apoptotic effect already after 5 h of culture, and down‐regulated autophagosome accumulation and beclin‐1 expression. The finding that factor(s) secreted by osteo‐differentiating MSCs shows properties of an apoptotic inducer and autophagy inhibitor on triple‐negative breast cancer cells may have an important applicative potential that deserves further investigation. Copyright © 2015 John Wiley & Sons, Ltd.     

Sap Concentrations in Halophytes and Some Other Plants

Freezing point depression in xylem sap of mangroves was found to range from 0.05 to 0.5 degrees , in desert plants from 0.01 to 0.16 degrees . In crush juices from leaves of Batis and Salicornia, 90% or more of the freezing point depression was made up of sodium and chlorine ions; in mangroves they constituted 50 to 70%, the rest probably being organic solutes. Plants growing in seawater have -30 to -60 atmospheres pressure in the xylem sap. As shown earlier, at zero turgor pressure the intracellular freezing point of the parenchyma cells matches closely the negative pressure in the xylem sap. This agrees with the present data, that the fluid which exudes from the xylem by applying gas pressure on the leaves is practically pure water; freezing point is rarely above 0.01 to 0.02 degrees . To perform this ultrafiltration, the plasma membrane is subjected to a hydrostatic pressure gradient which in some cases may exceed 100 atmospheres.     

Genetic variation in the Cytb gene of human cerebral Taenia solium cysticerci recovered from clinically and radiologically heterogeneous patients with neurocysticercosis

Neurocysticercosis (NC) is a clinically and radiologically heterogeneous parasitic disease caused by the establishment of larval Taenia solium in the human central nervous system. Host and/or parasite variations may be related to this observed heterogeneity. Genetic differences between pig and human-derived T. solium cysticerci have been reported previously. In this study, 28 cysticerci were surgically removed from 12 human NC patients, the mitochondrial gene that encodes cytochrome b was amplified from the cysticerci and genetic variations that may be related to NC heterogeneity were characterised. Nine different haplotypes (Ht), which were clustered in four haplogroups (Hg), were identified. Hg 3 and 4 exhibited a tendency to associate with age and gender, respectively. However, no significant associations were found between NC heterogeneity and the different T. solium cysticerci Ht or Hg. Parasite variants obtained from patients with similar NC clinical or radiological features were genetically closer than those found in groups of patients with a different NC profile when using the Mantel test. Overall, this study establishes the presence of genetic differences in the Cytb gene of T. solium isolated from human cysticerci and suggests that parasite variation could contribute to NC heterogeneity.     

Fractionation and characterization of boar seminal plasma spermadhesin PSP-II glycoforms reveal the presence of uncommon N-acetylgalactosamine-containing N-linked oligosaccharides

Lectin mapping, carbohydrate analysis and electrospray mass spectrometry of boar seminal plasma PSP-II glycoforms show that its single N-glycosylation site displays a repertoire of carbohydrate structures consisting of the basic pentasaccharide core Manα 1–6[Manα 1–3]Manβ1-4GlcNAcβ1-4GlcNAc with a fucosyl residue α1-6-linked to the innermost N-acetylglucosamine residue. Other glycoforms display fucosylated hybrid-type or monoantennary complex-type chains, some of which contain α2-6-linked sialic acid. N-acetylgalactosamine, possibly in Galβ1-3GalNAc sequence, is present in most of the PSP-II glycoforms. Abbreviations: PSP-I and PSP-II, porcine seminal plasma proteins I and II; PNGaseF, peptide-N4-(N-acetyl-β-D-glucosaminyl) asparagine amidase (EC 3.5.1.52) from Flavobacterium meningosepticum; ConA, Cannavalia ensiformis (jack bean) agglutinin; GNA, Galanthus nivalis (snowdrop) agglutin; SNA, Sambucus nigra (elderberry) agglutinin; MAA, Maackia amurensis (maakia) agglutinin; PNA, Arachis hypogaea (peanut) agglutinin; DSA, Datura stramonium (jimson weed) agglutinin; AAA, Aleuria aurantia agglutinin This revised version was published online in November 2006 with corrections to the Cover Date.     

Role of IFN-gamma and IL-6 in a protective immune response to <Emphasis Type="Italic"> Yersinia enterocolitica</Emphasis>in mice

Background  

Yersinia outer protein (Yop) H is a secreted virulence factor of Yersinia enterocolitica (Ye), which inhibits phagocytosis of Ye and contributes to the virulence of Ye in mice. The aim of this study was to address whether and how YopH affects the innate immune response to Ye in mice.