Embryonic development of pineal gland vesicles: a morphological and morphometrical study in chick embryos.

Pineal cell aggregates in 5, 10 and 15 day-old chick embryos have been studied. Cell aggregates were classified into rosettes or vesicles and spheroid and ellipsoid vesicles distinguished. The number of pineal vesicles per unit of surface (vesicle density) was determined in three pineal portions: apical, anterior and posterior. By day 5, only cellular rosettes were found, mainly in the apical portion. After 10 and 15 days, the presence of rosettes was occasional. The posterior wall showed only small spheroid vesicles, while in the apical and anterior areas ellipsoid vesicles were also observed. Moreover, the spheroid/ellipsoid vesicle ratio increased from the 10th to the 15th day of incubation. The vesicle density decreased between the 10th and 15th day because of the increase in both vesicle and pineal size, without changes in the total number of vesicles. The results suggest that changes in vesicle morphology and density could be related to the functional activity of the pineal gland during embryonic development.     

Hologenomic speciation: synergy between a male‐killing bacterium and sex‐linkage creates a ‘magic trait’ in a butterfly hybrid zone

Danaus chrysippus (L.) in Africa comprises four substantially isolated semispecies that are migratory and hybridize on a seasonal basis throughout the eastern and central part of the continent. In the hybrid zone (but not elsewhere), the butterfly is commonly host to a male killing endosymbiotic bacterium, Spiroplasma sp., which principally infects one semispecies, Danaus chrysippus chrysippus in Kenya. A W‐autosome mutation, inherited strictly matrilinearly, links B and C colour gene loci, which have thus gained sex‐linkage in chrysippus. We have monitored variation in sex ratio and genotype at the A and C colour gene loci for two extended periods of 18 months (2004–5) and 12 months (2009–10) in adults reared from wild eggs laid on trap plants in Kasarani, near Nairobi, Kenya. Additionally, in 2009–10, all surviving adult butterflies were screened for Spiroplasma infection. The hybridizing Kasarani population is highly atypical in three respects, and has apparently been so for some 30 years: first, the sex ratio is permanently female‐biased (as expected), although subject to seasonal fluctuation, being lowest (male/female) when D. c. chrysippus (cc) peaks and highest when Danaus chrysippus dorippus (CC) predominates; second, the population is invariably dominated by Cc heterozygotes of both sexes but especially females; and third, cc males are always scarce because they are systematically eliminated by male killing, whereas the CC genotype is male‐biased. It is this imbalance of sex versus genotype that determines the massive departure from Hardy–Weinberg equilibrium in the population, in part because cc females have little choice but to pair with C‐ males. We suggest that: first, Cc hybrids of both sexes fail to disperse in the company of either parental semispecies; second, Spiroplasma positive females carrying the W‐autosome mutation have a selective advantage over females that lack the translocation; third, the endoparasite and the translocation create a ‘magic trait’ linkage group that underlies hologenomic reproductive isolation between two emerging species, D. c. chrysippus and D. c. dorippus; and, fourth, that the predominance of males in dorippus suggests that individuals must be protected by a male‐killing suppressor gene. By contrast to the C locus, Aa heterozygotes are in substantial and permanent deficit, suggesting either assortative mating between AA (chrysippus and dorippus) and aa (Danaus chrysippus alcippus), or heterozygote unfitness, or both. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 92–109.     

Parasite Biomass-Related Inflammation,Endothelial Activation,Microvascular Dysfunction and Disease Severity in Vivax Malaria

Plasmodium vivax can cause severe malaria, however its pathogenesis is poorly understood. In contrast to P. falciparum, circulating vivax parasitemia is low, with minimal apparent sequestration in endothelium-lined microvasculature, and pathogenesis thought unrelated to parasite biomass. However, the relationships between vivax disease-severity and total parasite biomass, endothelial autocrine activation and microvascular dysfunction are unknown. We measured circulating parasitemia and markers of total parasite biomass (plasma parasite lactate dehydrogenase [pLDH] and PvLDH) in adults with severe (n = 9) and non-severe (n = 53) vivax malaria, and examined relationships with disease-severity, endothelial activation, and microvascular function. Healthy controls and adults with non-severe and severe falciparum malaria were enrolled for comparison. Median peripheral parasitemia, PvLDH and pLDH were 2.4-fold, 3.7-fold and 6.9-fold higher in severe compared to non-severe vivax malaria (p = 0.02, p = 0.02 and p = 0.015, respectively), suggesting that, as in falciparum malaria, peripheral P. vivax parasitemia underestimates total parasite biomass, particularly in severe disease. P. vivax schizonts were under-represented in peripheral blood. Severe vivax malaria was associated with increased angiopoietin-2 and impaired microvascular reactivity. Peripheral vivax parasitemia correlated with endothelial activation (angiopoietin-2, von-Willebrand-Factor [VWF], E-selectin), whereas markers of total vivax biomass correlated only with systemic inflammation (IL-6, IL-10). Activity of the VWF-cleaving-protease, ADAMTS13, was deficient in proportion to endothelial activation, IL-6, thrombocytopenia and vivax disease-severity, and associated with impaired microvascular reactivity in severe disease. Impaired microvascular reactivity correlated with lactate in severe vivax malaria. Findings suggest that tissue accumulation of P. vivax may occur, with the hidden biomass greatest in severe disease and capable of mediating systemic inflammatory pathology. The lack of association between total parasite biomass and endothelial activation is consistent with accumulation in parts of the circulation devoid of endothelium. Endothelial activation, associated with circulating parasites, and systemic inflammation may contribute to pathology in vivax malaria, with microvascular dysfunction likely contributing to impaired tissue perfusion.     

CNS delivery of l-dopa by a new hybrid glutathione–methionine peptidomimetic prodrug

Parkinson’s disease (PD) is a neurodegenerative disorder associated primarily with loss of dopamine (DA) neurons in the nigrostriatal system. With the aim of increasing the bioavailability of l-dopa (LD) after oral administration and of overcoming the pro-oxidant effect associated with LD therapy, we designed a peptidomimetic LD prodrug (1) able to release the active agent by enzyme catalyzed hydrolysis. The physicochemical properties, as well as the chemical and enzymatic stabilities of the new compound, were evaluated in order to check both its stability in aqueous medium and its sensitivity towards enzymatic cleavage, providing the parent LD drug, in rat and human plasma. The radical scavenging activities of prodrug 1 was tested by using both the DPPH–HPLC and the DMSO competition methods. The results indicate that the replacement of cysteine GSH portion by methionine confers resistance to oxidative degradation in gastric fluid. Prodrug 1 demonstrated to induce sustained delivery of DA in rat striatal tissue with respect to equimolar LD dosages. These results are of significance for prospective therapeutic application of prodrug 1 in pathological events associated with free radical damage and decreasing DA concentration in the brain.     

Bovine lactoferrin interacts with cable pili of Burkholderia cenocepacia

In this study we evaluated the ability of lactoferrin, the most abundant antimicrobial protein in airway secretions, to bind the surface structures of a Burkholderia strain cystic fibrosis-isolated. Burkholderia cenocepacia is a gram-negative bacterium involved as respiratory pathogen in cystic fibrosis patient infections. This bacterium possesses filamentous structures, named cable pili that have been proposed as virulence factors because of their ability to bind to respiratory epithelia and mucin. Previously, we demonstrated that bovine lactoferrin was able to influence the efficiency of invasion of different iron-regulated morphological forms of B. cenocepacia. Bovine lactoferrin showed to efficiently inhibit invasion of alveolar epithelial cells by free-living bacteria or iron-induced aggregates or biofilm. Results of the present study demonstrate that bovine lactoferrin is also able to specifically bind to B. cenocepacia cells and show that cable pili are involved in this interaction. The attachment of bovine lactoferrin to pili led to a reduced binding of bacterial cells to mucin. Since cable pili are implicated in mediating the bacterial interactions with mucin and epithelial cells, lactoferrin binding to these structures could play an important role in neutralizing bacterial infection in cystic fibrosis patients.     

Voltage-dependent Inwardly Rectifying Potassium Conductance in the Outer Membrane of Neuronal Mitochondria

Potassium fluxes integrate mitochondria into cellular activities, controlling their volume homeostasis and structural integrity in many pathophysiological mechanisms. The outer mitochondrial membrane (OMM) is thought to play a passive role in this process because K⁺ is believed to equilibrate freely between the cytosol and mitochondrial intermembrane space. By patch clamping mitochondria isolated from the central nervous systems of adult mitoCFP transgenic mice, we discovered the existence of I_OMMKi, a novel voltage-dependent inwardly rectifying K⁺ conductance located in the OMM. I_OMMKi is regulated by osmolarity, potentiated by cAMP, and activated at physiological negative potentials, allowing K⁺ to enter the mitochondrial intermembrane space in a controlled regulated fashion. The identification of I_OMMKi in the OMM supports the notion that a membrane potential could exist across this membrane in vivo and suggests that the OMM possesses regulated pathways for K⁺ uptake.     

Molecular biology of amyotrophic lateral sclerosis: insights from genetics

Amyotrophic lateral sclerosis (ALS) is a paralytic disorder caused by motor neuron degeneration. Mutations in more than 50 human genes cause diverse types of motor neuron pathology. Moreover, defects in five Mendelian genes lead to motor neuron disease, with two mutations reproducing the ALS phenotype. Analyses of these genetic effects have generated new insights into the diverse molecular pathways involved in ALS pathogenesis. Here, we present an overview of the mechanisms for motor neuron death and of the role of non-neuronal cells in ALS.