Post-transcriptional down-regulation of expression of transcription factor NF1 by Ha-ras oncogene.

NF1 is a family of polypeptides that binds to discrete DNA motifs and plays varying roles in the regulation of gene expression. These polypeptides are also thought to mediate the expression of differentiation-specific markers such as adipocyte and mammary cell type-specific genes. The expression of a number of cellular differentiation-specific markers is down-regulated during neoplastic transformation. We therefore investigated whether oncogenic transformation interferes with the action of NF1. Stable transfection of activated Ha-ras into a number of murine cells correlated with a down-regulation of the expression of the NF1 genes NF1/CTF and NF1/X. The down-regulation was not at the transcriptional level but at the level of stability of the NF1 mRNAs. The level of the DNA binding activity of the NF1 proteins was also reduced in Ha-v-ras-transformed cells, and the expression of a gene that depends on this family of transcription factors was specifically repressed. These results demonstrate that an activated Ha-ras-induced pathway destabilizes the half-life of mRNAs encoding specific members in the NF1 family of transcription factors, which leads to a decrease in NF1-dependent gene expression.

RAGBRAI Learn about the Land; Day 1, July 2011

Want to know what conditions to expect over the next stage of RAGBRAI? How hilly will it be, what towns and parks are between here and there, or what services are coming up in the next town?

RAGBRAI Learn about the Land; Day 2, July 2011

The University of Iowa Office of the State Archaeologist and Team Archaeology are back on RAGBRAI for another year of Archaeology on the Road, and pleased to partner this year with the IDNR: Geological and Water Survey and the U.S. Geological Survey under the theme “Human and Natural History Partners.” Archaeology on the Road brings you the unique cultural history and prehistory of Iowa on the RAGBRAI route, pointing out interesting and significant archaeological sites and sharing Iowa’s past along the way. Look for our booth at Expo and then again on Days 1, 5 and 6 on the route, and also keep an eye out for our Team Archaeology

RAGBRAI Learn about the Land; Day 3, July 2011

The University of Iowa Office of the State Archaeologist and Team Archaeology are back on RAGBRAI for another year of Archaeology on the Road, and pleased to partner this year with the IDNR: Geological and Water Survey and the U.S. Geological Survey under the theme “Human and Natural History Partners.” Archaeology on the Road brings you the unique cultural history and prehistory of Iowa on the RAGBRAI route, pointing out interesting and significant archaeological sites and sharing Iowa’s past along the way. Look for our booth at Expo and then again on Days 1, 5 and 6 on the route, and also keep an eye out for our Team Archaeology

RAGBRAI Learn about the Land; Day 4, July 2011

The University of Iowa Office of the State Archaeologist and Team Archaeology are back on RAGBRAI for another year of Archaeology on the Road, and pleased to partner this year with the IDNR: Geological and Water Survey and the U.S. Geological Survey under the theme “Human and Natural History Partners.” Archaeology on the Road brings you the unique cultural history and prehistory of Iowa on the RAGBRAI route, pointing out interesting and significant archaeological sites and sharing Iowa’s past along the way. Look for our booth at Expo and then again on Days 1, 5 and 6 on the route, and also keep an eye out for our Team Archaeology

RAGBRAI Learn about the Land; Day 5, July 2011

The University of Iowa Office of the State Archaeologist and Team Archaeology are back on RAGBRAI for another year of Archaeology on the Road, and pleased to partner this year with the IDNR: Geological and Water Survey and the U.S. Geological Survey under the theme “Human and Natural History Partners.” Archaeology on the Road brings you the unique cultural history and prehistory of Iowa on the RAGBRAI route, pointing out interesting and significant archaeological sites and sharing Iowa’s past along the way. Look for our booth at Expo and then again on Days 1, 5 and 6 on the route, and also keep an eye out for our Team Archaeology.

RAGBRAI Learn about the Land; Day 7, July 2011

The University of Iowa Office of the State Archaeologist and Team Archaeology are back on RAGBRAI for our third year of Archaeology on the Road, and pleased to partner this year with the IDNR: Geological and Water Survey and the U.S. Geological Survey under the theme “Human and Natural History Partners.” Archaeology on the Road brings you the unique cultural history and prehistory of Iowa on the RAGBRAI route, pointing out interesting and significant archaeological sites and sharing Iowa’s past along the way. Look for our booth at Expo and then again on Days 1, 5 and 6 on the route, and also keep an eye out for our Team Archaeology.

Calcium reabsorption in the distal tubule: regulation by sodium, pH, and flow.

We developed a mathematical model of Ca transport along the late distal convoluted tubule (DCT2) and the connecting tubule (CNT) to investigate the mechanisms that regulate Ca reabsorption in the DCT2-CNT. The model accounts for apical Ca influx across transient receptor potential vanilloid 5 (TRPV5) channels and basolateral Ca efflux via plasma membrane Ca-ATPase pumps and type 1 Na/Ca exchangers (NCX1). Model simulations reproduce experimentally observed variations in Ca uptake as a function of extracellular pH, Na, and Mg concentration. Our results indicate that amiloride enhances Ca reabsorption in the DCT2-CNT predominantly by increasing the driving force across NCX1, thereby stimulating Ca efflux. They also suggest that because aldosterone upregulates both apical and basolateral Na transport pathways, it has a lesser impact on Ca reabsorption than amiloride. Conversely, the model predicts that full NCX1 inhibition and parathyroidectomy each augment the Ca load delivered to the collecting duct severalfold. In addition, our results suggest that regulation of TRPV5 activity by luminal pH has a small impact, per se, on transepithelial Ca fluxes; the reduction in Ca reabsorption induced by metabolic acidosis likely stems from decreases in TRPV5 expression. In contrast, elevations in luminal Ca are predicted to significantly decrease TRPV5 activity via the Ca-sensing receptor. Nevertheless, following the administration of furosemide, the calcium-sensing receptor-mediated increase in Ca reabsorption in the DCT2-CNT is calculated to be insufficient to prevent hypercalciuria. Altogether, our model predicts complex interactions between calcium and sodium reabsorption in the DCT2-CNT.

Neural regulation of pancreatic islet cell mass and function.

Intracellular glucose signalling pathways control the secretion of glucagon and insulin by pancreatic islet α- and β-cells, respectively. However, glucose also indirectly controls the secretion of these hormones through regulation of the autonomic nervous system that richly innervates this endocrine organ. Both parasympathetic and sympathetic nervous systems also impact endocrine pancreas postnatal development and plasticity in adult animals. Defects in these autonomic regulations impair β-cell mass expansion during the weaning period and β-cell mass adaptation in adult life. Both branches of the autonomic nervous system also regulate glucagon secretion. In type 2 diabetes, impaired glucose-dependent autonomic activity causes the loss of cephalic and first phases of insulin secretion, and impaired suppression of glucagon secretion in the postabsorptive phase; in diabetic patients treated with insulin, it causes a progressive failure of hypoglycaemia to trigger the secretion of glucagon and other counterregulatory hormones. Therefore, identification of the glucose-sensing cells that control the autonomic innervation of the endocrine pancreatic and insulin and glucagon secretion is an important goal of research. This is required for a better understanding of the physiological control of glucose homeostasis and its deregulation in diabetes. This review will discuss recent advances in this field of investigation.

Iowa, The Land Between Two Rivers, 1950.

This brochure is designed as a brief pictorial travelogue on Iowa.

Microbial biomass and soil chemical properties under different land use systems in northeastern Pará

The increase in agricultural production in the Brazilian Amazon region is mostly a result of the agricultural frontier expansion, into areas previously influenced by humans or of native vegetation. At the same time, burning is still used to clear areas in small-scale agricultural systems, leading to a loss of the soil productive capacity shortly after, forcing the opening of new areas. This study had the objective of evaluating the effect of soil preparation methods that involve plant residue shredding, left on the surface or incorporated to the soil, with or without chemical fertilization, on the soil chemical and biological properties. The experiment was conducted in 1995, in an experimental field of Yellow Latosol (Oxisol) of the Embrapa Amazônia Oriental, northeastern Pará (Brazil). The experiment was arranged in randomized blocks, in a 2x6 factorial design, with two management systems and six treatments evaluated twice. The management systems consisted of rice (Oriza sativa), followed by cowpea (Vigna unguiculata) with manioc (Manihot esculenta). In the first system the crops were planted in two consecutive cycles, followed by a three-year fallow period (natural regrowth); the second system consisted of one cultivation cycle and was left fallow for three years. The following treatments were applied to the secondary forest vegetation: slash and burn, fertilized with NPK (Q+NPK); slash and burn, without fertilizer NPK (Q-NPK); cutting and shredding, leaving the residues on the soil surface, fertilized with NPK (C+NPK); cutting and shredding, leaving residues on the soil surface, without fertilizer (C-NPK); cutting and shredding, with residue incorporation and fertilized with NPK (I+NPK); cutting and shredding, with residue incorporation and without NPK fertilizer (I-NPK). The soil was sampled in the rainier season (April 2006) and in the drier season (September 2006), in the 0-0.1 m layer. From each plot, 10 simple samples were collected in order to generate a composite sample. In the more intensive management system the contents of microbial C (Cmic) and microbial N (Nmic) were higher, while the C (Corg) level was higher in the less intensive system. The treatments with highest Cmic and Nmic levels were those with cutting, shredding and distribution of biomass on the soil surface. Under both management systems, the chemical characteristics were in ranges that classify the soil as little fertile, although P and K (in the rainy season) were higher in the less intensive management system.

Site index curves for European aspen ( Populus tremula L.) growing on forest land of different soils in Sweden

Summary

Land-use systems affect Archaeal community structure and functional diversity in western Amazon soils

The study of the ecology of soil microbial communities at relevant spatial scales is primordial in the wide Amazon region due to the current land use changes. In this study, the diversity of the Archaea domain (community structure) and ammonia-oxidizing Archaea (richness and community composition) were investigated using molecular biology-based techniques in different land-use systems in western Amazonia, Brazil. Soil samples were collected in two periods with high precipitation (March 2008 and January 2009) from Inceptisols under primary tropical rainforest, secondary forest (5-20 year old), agricultural systems of indigenous people and cattle pasture. Denaturing gradient gel electrophoresis of polymerase chain reaction-amplified DNA (PCR-DGGE) using the 16S rRNA gene as a biomarker showed that archaeal community structures in crops and pasture soils are different from those in primary forest soil, which is more similar to the community structure in secondary forest soil. Sequence analysis of excised DGGE bands indicated the presence of crenarchaeal and euryarchaeal organisms. Based on clone library analysis of the gene coding the subunit of the enzyme ammonia monooxygenase (amoA) of Archaea (306 sequences), the Shannon-Wiener function and Simpson's index showed a greater ammonia-oxidizing archaeal diversity in primary forest soils (H' = 2.1486; D = 0.1366), followed by a lower diversity in soils under pasture (H' = 1.9629; D = 0.1715), crops (H' = 1.4613; D = 0.3309) and secondary forest (H' = 0.8633; D = 0.5405). All cloned inserts were similar to the Crenarchaeota amoA gene clones (identity > 95 %) previously found in soils and sediments and distributed primarily in three major phylogenetic clusters. The findings indicate that agricultural systems of indigenous people and cattle pasture affect the archaeal community structure and diversity of ammonia-oxidizing Archaea in western Amazon soils.