Aflatoxin M1 effects on Xenopus laevis development

BACKGROUND: The principal Aflatoxin B(1) (AFB(1)) hydroxylated metabolite excreted in milk is Aflatoxin M(1) (AFM(1)) classified in group 2B by the International Agency for Research on Cancer (IARC). Human exposure to AFM(1) is due to the consumption of contaminated dairy products and partly to endogenous production through AFB(1) liver metabolism. METHODS: Since no data are available on AFM(1) embryotoxicity, its lethal and teratogenic potential was investigated using the Frog Embryo Teratogenesis Assay-Xenopus (FETAX). Stage-8 blastulae were exposed to AFM(1) at 1, 4, 16, 64, and 256 microg/L concentrations until stage 47, free-swimming larva. RESULTS: A slight increase of mortality and malformed larva percents was found in AFM(1)-exposed groups but these differences were not statistically significant in comparison with the controls. CONCLUSIONS: Therefore, AFM(1) is a non-embryotoxic compound when evaluated with a FETAX model at concentrations under the conditions tested. However, AFM(1) merits further studies using mammals as experimental models to identify a possible risk during human pregnancy.     

Copper retention by a strain ofBacillus

Summary A survey has been made of the copper accumulation by resting cells of bacteria selected as copper-resistant, isolated from activated sludges. The best selected strain, classified asBacillus, retained copper at up to 3.8% of its cell dry weight. These values were lower in the presence of glucose, unlike a type culture ofBacillus cereus, in which the retention of copper was higher when glucose was present. Possible reasons for these changes in uptake of both strains are suggested.     

Iron metabolism genes in Antarctic notothenioids: A review

Iron is an essential element for metabolic processes intrinsic to life, but the properties that make iron a necessity also make it potentially deleterious. To avoid harm, iron homeostasis is achieved through iron transport, storage and regulatory proteins. The functions of some of these molecules are well described, for example transferrin and ferritin, whereas the roles of others remain unclear. The past decade has seen the identification of new molecules involved in iron metabolism, such as divalent metal transporter-1, and hepcidin. The present review aims at surveying the studies carried out on some of the most important genes involved in transport and storage of iron in Antarctic Notothenioidei, a dominating fish group endowed of a number of striking adaptive characters, including reduced (or absence of) hematocrit. This unique peculiarity among vertebrates makes this fish group a suitable system to studying the relationship between hemoglobin and iron metabolism and to understanding the adaptive changes occurred in Antarctic fish metabolism during their evolution to avoid the deleterious effects of iron overload in the absence of hemoglobin. The results summarised here indicate that the loss of hemoglobin in the most specialized group of Antarctic notothenioids, belonging to the Channychthyidae family, is accompanied by remodulation of the iron metabolism.     

CD8+ CD28- T regulatory lymphocytes inhibiting T cell proliferative and cytotoxic functions infiltrate human cancers

Tumor growth is allowed by its ability to escape immune system surveillance. An important role in determining tumor evasion from immune control might be played by tumor-infiltrating regulatory lymphocytes. This study was aimed at characterizing phenotype and function of CD8+ CD28- T regulatory cells infiltrating human cancer. Lymphocytes infiltrating primitive tumor lesion and/or satellite lymph node from a series of 42 human cancers were phenotypically studied and functionally analyzed by suppressor assays. The unprecedented observation was made that CD8+ CD28- T regulatory lymphocytes are almost constantly present and functional in human tumors, being able to inhibit both T cell proliferation and cytotoxicity. CD4+ CD25+ T regulatory lymphocytes associate with CD8+ CD28- T regulatory cells so that the immunosuppressive activity of tumor-infiltrating regulatory T cell subsets, altogether considered, may become predominant. The infiltration of regulatory T cells seems tumor related, being present in metastatic but not in metastasis-free satellite lymph nodes; it likely depends on both in situ generation (via cytokine production) and recruitment from the periphery (via chemokine secretion). Collectively, these results have pathogenic relevance and implication for immunotherapy of cancer.     

Adrenergic origin of very low-frequency blood pressure oscillations in the unanesthetized rat

Spectral analysis of cardiovascular signals has been extensively used to investigate circulatory homeostatic mechanisms. However, the nature of very low-frequency (VLF) fluctuations remains unclear. Because we previously observed enhanced VLF fluctuations in blood pressure (BP) in the sympathectomized rat (a model characterized by markedly increased plasma epinephrine levels), the aims of our study were to assess whether the genesis of VLF fluctuations in BP depends on circulating catecholamines and to determine which adrenergic receptor(s) and which membrane ion channel(s) are involved. We used continuous intra-arterial BP recordings from unanesthetized unrestrained rats to compute the power of VLF fluctuations in BP in the intact condition, during acute ganglionic blockade with hexamethonium, and after restoration of BP levels by infusion (in addition to hexamethonium) of adrenergic agonists (epinephrine, norepinephrine, and clonidine) or nonadrenergic vasoconstrictors (vasopressin). Effects of infusion of specific adrenergic receptor blockers (propranolol, prazosin, and yohimbine) with hexamethonium and catecholamines and infusion of various membrane ion channel blockers on VLF fluctuations in BP were also evaluated. Our results are as follows. 1) Ganglionic blockade drastically reduced BP levels and VLF fluctuations. 2) All vasoconstrictors restored BP levels, but only adrenergic vasoconstrictors generated striking VLF fluctuations in BP. 3) Catecholamine-induced fluctuations were abolished by alpha2-, but not alpha1- or beta-, adrenergic receptor blockade and by Ba2+-sensitive K+ channel or L-type Ca2+ channel, but not by other ion channel, blockers. We conclude that, in the conscious, unrestrained ganglion-blocked rat, catecholamine infusion generates VLF fluctuations in BP through stimulation of alpha2-receptors and activation of Ba2+-sensitive K+ channels. These fluctuations may have (patho)physiological relevance under conditions of disrupted circulatory homeostasis.     

Wolbachia Reduces the Transmission Potential of Dengue-Infected Aedes aegypti

BackgroundDengue viruses (DENV) are the causative agents of dengue, the world’s most prevalent arthropod-borne disease with around 40% of the world’s population at risk of infection annually. Wolbachia pipientis, an obligate intracellular bacterium, is being developed as a biocontrol strategy against dengue because it limits replication of the virus in the mosquito. The Wolbachia strain wMel, which has been introduced into the mosquito vector, Aedes aegypti, has been shown to invade and spread to near fixation in field releases. Standard measures of Wolbachia’s efficacy for blocking virus replication focus on the detection and quantification of virus in mosquito tissues. Examining the saliva provides a more accurate measure of transmission potential and can reveal the extrinsic incubation period (EIP), that is, the time it takes virus to arrive in the saliva following the consumption of DENV viremic blood. EIP is a key determinant of a mosquito’s ability to transmit DENVs, as the earlier the virus appears in the saliva the more opportunities the mosquito will have to infect humans on subsequent bites.Conclusions/SignificanceThe saliva-based traits reported here offer more disease-relevant measures of Wolbachia’s effects on the vector and the virus. The lengthening of EIP highlights another means, in addition to the reduction of infection frequencies and DENV titers in mosquitoes, by which Wolbachia should operate to reduce DENV transmission in the field.     

Structure and expression of genes involved in transport and storage of iron in red-blooded and hemoglobin-less antarctic notothenioids

Antarctic notothenioids are characterized by a drastic reduction of the hemoglobin content, a condition that reaches its extreme in icefish that, following a gene deletion event, are completely devoid of hemoglobin. To answer the question on what type of adaptive changes occurred in icefish to prevent accumulation of potentially dangerous ferrous iron, we investigated the genes of four proteins known to play a key role in iron metabolism. For this purpose, we cloned and sequenced the cDNAs encoding ceruloplasmin, transferrin, ferritin and divalent metal transporter 1. While the inferred amino acid sequences of transferrin from different Antarctic fish species showed a high level of similarity with the homologous proteins from other species, ceruloplasmin sequence featured amino acid substitutions affecting a copper binding site. Another peculiarity was the presence in subunit H of the icefish ferritin of the two sets of sites involved in iron oxidation and iron mineralization, which in mammals are located on two distinct ferritin subunits. Significant differences in the expression levels of the four genes were found between hemoglobinless and red-blooded notothenioids. An increased expression of ceruloplasmin mRNA in icefish was interpreted as a compensatory mechanism to prevent accumulation of ferrous iron in hemoglobinless fish. In icefish, the amounts of ferritin H-chain mRNA measured in liver, blood and head kidney were lower than in the same organs of the red-blooded fish. In the spleen of both fishes, the expression levels of ferritin H-chain were significantly lower than in the spleen of a "pink-blooded" notothenioid with an intermediate hemoglobin content. Finally, the amount of divalent metal transporter mRNA measured in the head-kidney was lower in the icefish than in the same organ of its red-blooded counterpart. These results indicate that the loss of hemoglobin in icefish is accompanied by remodulation of the iron metabolism.     

Priming xylem for stress recovery depends on coordinated activity of sugar metabolic pathways and changes in xylem sap pH

Some plant species are capable of significant reduction of xylem embolism during recovery from drought despite stem water potential remains negative. However, the functional biology underlying this process is elusive. We subjected poplar trees to drought stress followed by a period of recovery. Water potential, hydraulic conductivity, gas exchange, xylem sap pH, and carbohydrate content in sap and woody stems were monitored in combination with an analysis of carbohydrate metabolism, enzyme activity, and expression of genes involved in sugar metabolic and transport pathways. Drought resulted in an alteration of differential partitioning between starch and soluble sugars. Upon stress, an increase in the starch degradation rate and the overexpression of sugar symporter genes promoted the efflux of disaccharides (mostly maltose and sucrose) to the apoplast. In turn, the efflux activity of the sugar‐proton cotransporters caused a drop in xylem pH. The newly acidic environment induced the activity of apoplastic invertases leading to the accumulation of monosaccharides in the apoplast, thus providing the main osmoticum necessary for recovery. During drought and recovery, a complex network of coordinated molecular and biochemical signals was activated at the interface between xylem and parenchyma cells that appeared to prime the xylem for hydraulic recovery.     

Romina: A powerful strawberry with in vitro efficacy against uterine leiomyoma cells

Uterine leiom yomas are benign tumors highly prevalent in reproductive women. In thecurrent study, initially, we aimed to screen five different strawberry cultivars (Alba, Clery, Portola, Tecla, and Romina) to identify efficient cultivars in terms of phytochemical characterization and biological properties by measuring phenolic and anthocyanin content as well as antioxidant capacity, and by measuring apoptotic rate and reactive oxygen species (ROS) production in uterine leiomyoma cells. Next, we focused on the most efficient ones, cultivar Alba (A) and Romina (R) as well as Romina anthocyanin (RA) fraction for their ability to regulate oxidative phosphorylation (oxygen consumption rate [OCR]) glycolysis (extracellular acidification rate [ECAR]), and also fibrosis. Leiomyoma and myometrial cells were treated with a methanolic extract of A and R (250 μg/ml) or with RA (50 μg/ml) for 48 hr to measure OCR and ECAR, as well as gene expression associated with fibrosis. In the leiomyoma cells, RA was more effective in inducing apoptosis and increasing intracellular ROS levels, followed by R and A. In myometrial cells, all strawberry treatments increased the cellular viability and decreased ROS concentrations. Leiomyoma cells showed also a significant decrease in ECAR, especially after RA treatment, while OCR was slightly increased in both myometrial and leiomyoma cells. R and RA treatment significantly decreased collagen 1A1, fibronectin, versican, and activin A messenger RNA expression in leiomyoma cells. In conclusion, this study suggests that Romina, or its anthocyanin fraction, can be developed as a therapeutic and/or preventive agent for uterine leiomyomas, confirming the healthy effects exerted by these fruits and their bioactive compounds.     

Organization and nucleotide sequence of the genes for ribosomal protein S2 and elongation factor Ts in Spirulina Platensis

A 6.5 kb region from the genome of the cyanobacterium Spirulina platensis was cloned using as a probe the Escherichia coli gene for ribosomal protein S2. Sequence analysis revealed, in this region, the presence of the gene for ribosomal protein S2 and part of the gene for the elongation factor Ts (EF-Ts). The arrangement rpsB-spacer-tsf resembles that reported for E. coli. The deduced amino acid sequences of the platensis S2 and EF-Ts show significant homology with the E. coli counterparts.