Structure of an exocellular polysaccharide produced by Streptococcus thermophilus

Streptococcus thermophilus strains grown on skimmed milk produced a viscosifying, exocellular, and water-soluble polysaccharide which contains D-glucose, D-galactose, and N-acetyl-D-galactosamine in the ratio of 1:2:1. Methylation analysis identified the glycosidic linkages in the tetrasaccharidic repeating-unit, and Smith degradation and nitrous deamination after N-deacetylation gave the sequence of monosaccharides in the repeating-unit. The anomeric configurations of the sugar residues were determined by oxidation of the peracetylated polysaccharide with chromium trioxide and by 1H- and 13C-n.m.r. spectroscopy. The following structure was assigned to the repeating unit of the polysaccharide,----3)-beta-D-Galp-(1----3)-[alpha-D-Galp-(1----6)]-beta- D- Glcp-(1----3)-alpha-D-GalpNAc-(1----.     

Thiocyanate transport across fish intestine (Pleuronectes platessa)

Summary When bathed on both sides with identical chloride-containing salines thein vitro preparation of the plaice intestine maintains a negative (serosa to mucosa) short-circuit current of 107±11 A/cm², a transepithelial potential difference of 5.5±0.6 mV (serosa negative), and a mean mucosal membrane potential of –45.4±0.6 mV. Under these conditions the intracellular chloride activity is 32mm.If chloride in the bathing media is partially, or completely substituted by thiocyanate the measured electrical parameters do not change but transepithelial flux determinations show a reduction in chloride fluxes and the presence of a significant thiocyanate flux. The addition of piretanide (10^–4 m) reduced the short-circuit current and the mucosa-to-serosa fluxes of chloride and thiocyanate; this inhibition is similar to the effect of piretanide on chloride transport in this tissue.The results indicate that thiocyanate is transported in this tissue via the piretanide-sensitive chloride pathway and are compared with the effects of thiocyanate on other tissues reported in the literature.     

Genomic Signatures of Recent Adaptation in a Wild Bumblebee

Environmental changes threaten insect pollinators, creating risks for agriculture and ecosystem stability. Despite their importance, we know little about how wild insects respond to environmental pressures. To understand the genomic bases of adaptation in an ecologically important pollinator, we analyzed genomes of Bombus terrestris bumblebees collected across Great Britain. We reveal extensive genetic diversity within this population, and strong signatures of recent adaptation throughout the genome affecting key processes including neurobiology and wing development. We also discover unusual features of the genome, including a region containing 53 genes that lacks genetic diversity in many bee species, and a horizontal gene transfer from a Wolbachia bacteria. Overall, the genetic diversity we observe and how it is distributed throughout the genome and the population should support the resilience of this important pollinator species to ongoing and future selective pressures. Applying our approach to more species should help understand how they can differ in their adaptive potential, and to develop conservation strategies for those most at risk.     

Active immunization combined with cisplatin confers enhanced therapeutic protection and prevents relapses of HPV-induced tumors at different anatomical sites

The active immunotherapy concept relies on the use of vaccines that are capable of inducing antitumor immunity, reversion of the suppressive immunological environment, and long-term memory responses. Previously, antitumor vaccines based on a recombinant plasmid (pgDE7h) or a purified protein (gDE7) led to regression of early-established human papillomavirus (HPV)-associated tumors in a preclinical model. In this work, the anticancer vaccines were combined with cisplatin to treat HPV-induced tumors at advanced growth stages. The antitumor effects were evaluated in terms of tumor regression, induction of specific CD8⁺ T cells, and immune modulation of the tumor microenvironment. Acute toxicity induced by the treatment was measured by weight loss and histological alterations in the liver and kidneys. Our results revealed that the combination of cisplatin with either one of the tested immunotherapies (pgDE7h or gDE7) led to complete tumor regression in mice. Also, the combined treatment resulted in synergistic effects, particularly among mice immunized with gDE7, including activation of systemic and tumor-infiltrating E7-specific CD8⁺ T cells, tumor infiltration of macrophages and dendritic cells, and prevention of tumor relapses at different anatomical sites. Furthermore, the protocol allowed the reduction of cisplatin dosage and its intrinsic toxic effects, without reducing antitumor outcomes. These results expand our knowledge of active immunotherapy protocols and open perspectives for alternative treatments of HPV-associated tumors.     

In vivo nuclear magnetic resonance studies of glycolytic kinetics in Lactococcus lactis.

The metabolism of glucose by nongrowing cells of L. lactis strain MG5267 was studied under controlled conditions of pH, temperature, and gas atmosphere (anaerobic and aerobic) using a circulating system coupled to nuclear magnetic resonance (NMR) detection that allowed a noninvasive determination of intracellular pools of intermediate metabolites by 13C-NMR with a time resolution of 30 seconds. In addition, intracellular parameters, such as pH, NTP levels, and concentration of inorganic phosphate in the cytoplasm, could be monitored on-line by 31P-NMR with a time resolution of approx. 3 min. The time course for the concentrations of intracellular fructose 1,6-bisphosphate (FBP), 3-phosphoglycerate (3-PGA), and phosphoenolpyruvate (PEP), together with kinetic measurements of substrate consumption and endproducts formation, were used as a basis for the construction of a mechanistic model for glycolysis. In vivo measurements were complemented with determinations of phosphorylated metabolites in perchloric acid extracts. A top-down model was developed by simplifying the metabolism to the resolution allowed by the experimental data collected by in vivo NMR (grouped in seven metabolic steps). This simplified mechanistic model was adjusted to the metabolite concentrations determined by in vivo NMR. The results obtained led to the rationalization of the dynamics of glucose metabolism as being driven largely by ATP surplus. This excess causes accumulation of FBP due to NAD+ limitation, whose regeneration is dependent on downstream pyruvate reduction. The model was capable of predicting qualitative shifts in the metabolism of glucose when changing from anaerobic to aerobic conditions.     

Melatonin blocks the activation of estrogen receptor for DNA binding.

The present study shows that melatonin prevents, within the first cell cycle, the estradiol-induced growth of synchronized MCF7 breast cancer cells. By using nuclear extracts of these cells, we first examined the binding of estradiol-estrogen receptor complexes to estrogen-responsive elements and found that the addition of estradiol to whole cells activates the binding of the estrogen receptor to DNA whereas melatonin blocks this interaction. By contrast, melatonin neither affects the binding of estradiol to its receptor nor the receptor nuclear localization. Moreover, we also show that addition of estradiol to nuclear extracts stimulates the binding of estrogen receptor to DNA, but this activation is also prevented by melatonin. The inhibitory effect caused by melatonin is saturable at nanomolar concentrations and does not appear to be mediated by RZR nuclear receptors. The effect is also specific, since indol derivatives do not cause significant inhibition. Furthermore, we provide evidence that melatonin does not interact with the estrogen receptor in the absence of estradiol. Together, these results demonstrate that melatonin interferes with the activation of estrogen receptor by estradiol. The effect of melatonin suggests the presence of a receptor that, upon melatonin addition, destabilizes the binding of the estradiol-estrogen receptor complex to the estrogen responsive element.