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Members of the archaeal phylum Bathyarchaeota are widespread and abundant in the energy-deficient marine subsurface sediments. However, their life strategies have remained largely elusive. Here, we provide genetic evidence that some lineages of Bathyarchaeota are acetogens, being capable of homoacetogenesis, a metabolism so far restricted to the domain Bacteria. Metabolic reconstruction based on genomic bins assembled from the metagenome of deep-sea subsurface sediments shows that the metabolism of some lineages of Bathyarchaeota is similar to that of bona fide bacterial homoacetogens, by having pathways for acetogenesis and for the fermentative utilization of a variety of organic substrates. Heterologous expression and activity assay of the acetate kinase gene ack from Bathyarchaeota, demonstrate further the capability of these Bathyarchaeota to grow as acetogens. The presence and expression of bathyarchaeotal genes indicative of active acetogenesis was also confirmed in Peru Margin subsurface sediments where Bathyarchaeota are abundant. The analyses reveal that this ubiquitous and abundant subsurface archaeal group has adopted a versatile life strategy to make a living under energy-limiting conditions. These findings further expand the metabolic potential of Archaea and argue for a revision of the role of Archaea in the carbon cycle of marine sediments.

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BACKGROUND: Acetate is an end-product of the PPi-dependent fermentative glycolysis in Entamoeba histolytica; it is synthesized from acetyl-CoA by ADP-forming acetyl-CoA synthetase (ACS) with net ATP synthesis or from acetyl-phosphate by a unique PPi-forming acetate kinase (AcK). The relevance of these enzymes to the parasite ATP and PPi supply, respectively, are analyzed here. METHODS: The recombinant enzymes were kinetically characterized and their physiological roles were analyzed by transcriptional gene silencing and further metabolic analyses in amoebae. RESULTS: Recombinant ACS showed higher catalytic efficiencies (Vmax/Km) for acetate formation than for acetyl-CoA formation and high acetyl-CoA levels were found in trophozoites. Gradual ACS gene silencing (49-93%) significantly decreased the acetate flux without affecting the levels of glycolytic metabolites and ATP in trophozoites. However, amoebae lacking ACS activity were unable to reestablish the acetyl-CoA/CoA ratio after an oxidative stress challenge. Recombinant AcK showed activity only in the acetate formation direction; however, its substrate acetyl-phosphate was undetected in axenic parasites. AcK gene silencing did not affect acetate production in the parasites but promoted a slight decrease (10-20%) in the hexose phosphates and PPi levels. CONCLUSIONS: These results indicated that the main role of ACS in the parasite energy metabolism is not ATP production but to recycle CoA for glycolysis to proceed under aerobic conditions. AcK does not contribute to acetate production but might be marginally involved in PPi and hexosephosphate homeostasis. SIGNIFICANCE: The previous, long-standing hypothesis that these enzymes importantly contribute to ATP and PPi supply in amoebae can now be ruled out.

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The genome of the Antarctic bacterium Pseudomonas extremaustralis was analyzed searching for genes involved in environmental adaptability focusing on anaerobic metabolism, osmoregulation, cold adaptation, exopolysaccharide production and degradation of complex compounds. Experimental evidences demonstrated the functionality of several of these pathways, including arginine and pyruvate fermentation, alginate production and growth under cold conditions. Phylogenetic analysis along with genomic island prediction allowed the detection of genes with probable foreign origin such as those coding for acetate kinase, osmotic resistance and colanic acid biosynthesis. These findings suggest that in P. extremaustralis the horizontal transfer events and/or gene redundancy could play a key role in the survival under unfavorable conditions. Comparative genome analysis of these traits in other representative Pseudomonas species highlighted several similarities and differences with this extremophile bacterium.

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Tyrosine kinase inhibitors have changed the management and outcomes of chronic myeloid leukemia patients. Quantitative polymerase chain reaction is used to monitor molecular responses to tyrosine kinase inhibitors. Molecular monitoring represents the most sensitive tool to judge chronic myeloid leukemia disease course and allows early detection of relapse. Evidence of achieving molecular response is important for several reasons: 1. early molecular response is associated with major molecular response rates at 18-24 months; 2. patients achieving major molecular response are less likely to lose their complete cytogenetic response; 3. a durable, stable major molecular response is associated with increased progression-free survival. However, standardization of molecular techniques is still challenging.

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Escherichia coli phosphotransacetylase (Pta) catalyzes the reversible interconversion of acetyl-CoA and acetyl phosphate. Both compounds are critical in E. coli metabolism, and acetyl phosphate is also involved in the regulation of certain signal transduction pathways. Along with acetate kinase, Pta plays an important role in acetate production when E. coli grows on rich medium; alternatively, it is involved in acetate utilization at high acetate concentrations. E. coli Pta is composed of three different domains, but only the C-terminal one, called PTA_PTB, is specific for all Ptas. In the present work, the characterization of E. coli Pta and deletions from the N-terminal region were performed. E. coli Pta acetyl phosphate-forming and acetyl phosphate-consuming reactions display different maximum activities, and are differentially regulated by pyruvate and phosphoenolpyruvate. These compounds activate acetyl phosphate production, but inhibit acetyl-CoA production, thus playing a critical role in defining the rates of the two Pta reactions. The characterization of three truncated Ptas, which all display Pta activity, indicates that the substrate-binding site is located at the C-terminal PTA_PTB domain. However, the N-terminal P-loop NTPase domain is involved in expression of the maximal catalytic activity, stabilization of the hexameric native state, and Pta activity regulation by NADH, ATP, phosphoenolpyruvate, and pyruvate. The truncated protein Pta-F3 was able to complement the growth on acetate of an E. coli mutant defective in acetyl-CoA synthetase and Pta, indicating that, although not regulated by metabolites, the Pta C-terminal domain is active in vivo.

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Este estudo teve por objetivo avaliar o estado nutricional, incluindo a prevalência de anemia, de crianças Kamaiurá, povo indígena do Alto Xingu, Brasil Central. Foram estudadas 112 crianças menores de dez anos de idade em 2000/2001. O perfil do crescimento infantil foi descrito segundo a distribuição dos índices altura/idade e peso/altura expressos em escore-z da população de referência do National Center of Health Statistics - NCHS. Os diagnósticos de déficit de altura e da relação peso/altura e o diagnóstico de obesidade corresponderam, respectivamente, aos valores abaixo de -2 escores-z de altura/idade e peso/altura e aos valores acima de 2 escores-z de peso/altura. O diagnóstico de anemia foi determinado a partir de concentrações de hemoglobina sérica inferiores a 11 g/dl para crianças entre seis meses e cinco anos de idade e inferiores a 11,5 g/dl para as crianças com idade entre cinco e dez anos incompletos, conforme recomendação da OMS. Aproximadamente um terço das crianças apresentou déficit de crescimento, enquanto déficit de peso/altura e obesidade não foram diagnosticados entre elas. A anemia esteve presente em mais da metade das crianças índias estudadas, 15 por cento delas apresentando anemia grave. Há necessidade de implementação de ações que visem a melhoria das condições socioambientais, de saúde e nutrição desse povo indígena.

In order to evaluate nutritional and anemic status, 112 Indian children (Kamaiurá), aged from 0 to 119.9 months, from the Alto Xingu region of central Brazil were studied in 2000/2001. The international growth reference - NCHS was used to evaluate height and weight, according to the child's age and gender. Growth deficit (stunting) and low weight status (wasting) were determined when height-for-age and weight-for-height indices were below _2 z scores, respectively, and obesity status when the weight-for-height index was above 2 z scores. Stunting was observed in 1/3 of the children and neither wasting nor obesity were observed. The anemic status was diagnosed by hemoglobin values below 11 g/dl for children from 6 to 59 months of age, and below 11.5 g/dl, for children from 60 to 119.9 months. About 50 percent of the Indian children were anemic and 15 percent were affected by severe anemia. There is a particular need to ensure efforts to implement environment, health and nutrition programs addressed to Kamaiurá children.

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