Extraction of hemicellulosic oligosaccharides from spruce using microwave oven or steam treatment

This paper describes the extraction of hemicellulosic oligosaccharides from spruce, using microwave or steam treatment that can be used for the production of polymers, replacing fossil-based polymers, e.g., hydrogels. The highest yield of oligosaccharides, measured as mannan, was 70% obtained with treatment in the microwave oven at 200 degrees C for 5 min. The amount of oligosaccharides extracted was 12.5 g per 100 g of dry wood. The molecular weights of some selected samples were analyzed using fast protein liquid chromatography and size exclusion chromatography and time-of-flight matrix-assisted laser desorption ionization. Recovered oligosaccharides following steam treatment at 200 degrees C for 2 min had a mean molecular weight of 3400 g/mol with a maximum weight of 12000 g/mol. Higher severity, i.e., increased temperature (>200 degrees C) and residence time, resulted in lower mean molecular weights and yield. Oligosaccharides with higher mean molecular weights were obtained at lower severity, but the yield was considerably lower. The feasibility of using the extracted hemicellulosic oligosaccharides from spruce for the synthesis of hydrogels was demonstrated.     

Thick ascending tubular cells in the loop of Henle: regulation of electrolyte homeostasis

Renal medullary tubular cells in the loop of Henle have crucial importance for the regulation of homeostasis of the extracellular fluid. These cells receive limited amount of blood and oxygen, and are also constantly challenged by the hypertonic environment. The medullary tubular cells in the last part of the loop of Henle have one of the highest known contents of mitochondria of all mammalian cells, reflecting their need for oxidative metabolism in order to sustain high ATP production for active transepithelial electrolyte transport. The commonly used diureticum furosemide targets one of the transporters present in these tubular cells with resulting diuresis. Several pathological states are associated with altered function of the medullary tubular cells, and the nephrotoxic substances tacrolimus and cyclosporine act on these cells. The specific Tamm-Horsfall glycoprotein is produced by medullary tubular cells. Alteration in the urinary excretion of this protein is used as marker of tubular damage.     

Structure and interactions of the carboxyl terminus of striated muscle alpha-tropomyosin: it is important to be flexible

Tropomyosin (TM) binds to and regulates the actin filament. We used circular dichroism and heteronuclear NMR to investigate the secondary structure and interactions of the C terminus of striated muscle alpha-TM, a major functional determinant, using a model peptide, TM9a(251-284). The (1)H(alpha) and (13)C(alpha) chemical shift displacements show that residues 252 to 277 are alpha-helical but residues 278 to 284 are nonhelical and mobile. The (1)H(N) and (13)C' displacements suggest that residues 257 to 269 form a coiled coil. Formation of an "overlap" binary complex with a 33-residue N-terminal chimeric peptide containing residues 1 to 14 of alpha-TM perturbs the (1)H(N) and (15)N resonances of residues 274 to 284. Addition of a fragment of troponin T, TnT(70-170), to the binary complex perturbs most of the (1)H(N)-(15)N cross-peaks. In addition, there are many new cross-peaks, showing that the binding is asymmetric. Q263, in a proposed troponin T binding site, shows two sets of side-chain (15)N-(1)H cross-peaks, indicating conformational flexibility. The conformational equilibrium of the side chain changes upon formation of the binary and ternary complexes. Replacing Q263 with leucine greatly increases the stability of TM9a(251-284) and reduces its ability to form the binary and ternary complexes, showing that conformational flexibility is crucial for the binding functions of the C terminus.     

Nitrogen and Phosphorus Release from Decomposing Leaves under Sub‐Humid Tropical Conditions1

For many soils of the tropics, inputs of organic materials are essential to sustain soil fertility and crop production. Research in the quality of organic inputs, a key factor controlling rates of decomposition and nutrient release, continues to guide selection and use of organic materials as nutrient sources. The relationship between decomposition patterns and the quality parameters of the fresh leaves of six agroforestry species: Sesbania sesban, Croton megalocarpus, Calliandra calothyrsus, Tithonia diversifolia, Lantana camara, and Senna spectabilis, was investigated in a litterbag study over a period of 77 days in the highlands of western Kenya. The litterbags were buried 1 cm below the soil surface and covered with soil of ca 1 cm thickness. Percent leaf mass and total N and P that remained with time strongly correlated with total P and C/P ratio (R²= 0.60‐0.90) during the first 35 days of study; but afterwards, correlation was stronger with the initial soluble polyphenolics (Pp)/P ratio (R²= 0.69‐0.92) than with total P and C/P ratio. Loss of leaf mass and release of N and P followed the exponential function, y_t= y₀* e‐^kt, from which the specific decay rate constants (k) were calculated for loss of leaf mass (k_B) and release of N (k_N) and P (K_p). Among the plant species, the k values were lowest in Calliandra with k_B= 0.012/d, k_N= 0.017/d and k_p= 0.044/d. Lantana had the highest K values with k_g= 0.067/d and k_p= 0.119/d, but the highest k_N value of 0.109/d occurred in Tithonia. The k_B values for all organic materials were lower than their corresponding k_N and k_p values, suggesting that leaching of N and P from litters may have augmented the microbial mineralization of N and P. There was a strong correlation between the k_B, k_N, and k_p values and total P (r = 0.82‐0.96; P 0.01), but not total N, lignin (LIG), or Pp. Rates of N and P release followed the general trend: Tithonia > Senna > Lantana > Sesbania > Croton > Calliandra. The results indicated that, among the quality parameters studied, total P is the most important factor controlling rate of decomposition and N and P release from organic inputs in the area of study.     

Analysis of the site-specific asparagine-linked glycosylation of recombinant human coagulation factor VLLa by glycosidase digestions, liquid chromatography, and mass spectrometry

The two asparagine-linked glycosylation sites of recombinant coagulation factor VIIa have been characterized by glycosidase digestions, size-exclusion chromatography (SEC), and mass spectrometry (MS). Nine structures were characterized as core fucosylated bi- and triantennary structures with 0-3 sialic-acid residues, which were alpha2-3 linked to galactose exclusively. Three of the structures had one or two galactose residues substituted by N-acetylgalactosamine. Significant differences were found between the oligosac-charide profiles for the two glycosylation sites in rFVIIa. At Asn322, the degree of sialylation was lower and higher amounts of structures containing N-acetylgalactosamine were found compared to Asn l45.     

Mapping studies and expression of genes located on human chromosome 11, band q23

Chromosome translocations and deletions may alter cellular proto-oncogenes and result in cellular changes that are important in the pathogenesis of malignancy. The region 11q23 is frequently involved in human malignancy. Utilizing a leukemic cell line with a reciprocal translocation involving 11q23 and somatic cell hybrids derived from this cell line, we analyzed five genes assigned to 11q23: NCAM, CD3D, CD3E, THY1, and ETS1. Our data showed no evidence of direct involvement of these genes in this leukemia but enabled a partial genetic map of this important region of the human genome to be constructed: 11cen--NCAM--CD3([G, D], E)--parallel--(ETS1, THY1)--11qter.