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41.
Leaching of soluble substances may be an important first step in leaf litter decomposition in small streams, but recent research has suggested that large leaching losses (up to 30% of initial mass in 48 h) may be an artifact created by using air-dried leaves in decomposition experiments. In laboratory experiments, we compared 3 d leaching losses from freshly fallen and air-dried senescent leaves of 27 tree species from different regions across Canada. Air-dried leaves from all species leached measurable amounts of original mass (3.6–32.8% dry mass), but leaching losses from fresh leaves (0–35%) were detectable in all but two species. Air-drying increased leaching losses in many species, but in others it reduced leaching losses or had no measurable effect. Results for leaves of the same species collected in different regions or in different years were generally similar, but species within the same genus often behaved very differently. Neither moisture content (fresh or air-dried), leaf thickness, nor cuticle thickness proved of any value as predictors of leaching losses or the effect of air-drying. The propensity of autumn-fallen leaves to leach, whether fresh or air-dried, appears to be a property of the individual tree species. 相似文献
42.
J. L. Marco L. A. Bataus F. F. Valência C. J. Ulhoa S. Astolfi-Filho C. R. Felix 《Applied microbiology and biotechnology》1996,44(6):746-752
ABacillus subtilis amylase gene was inserted into a plasmid which transferred toEscherichia coli. During cloning, a 3 region encoding 171 carboxyterminal amino acids was replaced by a nucleotide sequence that encoded 33 amino acid residues not present in the indigenous protein. The transformed cells produced substantial amylolytic activity. The active protein was purified to apparent homogeneity. Its molecular mass (48 kDa), as estimated in sodium dodecyl sulfate/polyacrylamide gel electrophoresis, was lower than the molecular mass values calculated from the derived amino acid sequences of theB. subtilis complete -amylase (57.7 kDa) and the truncated protein (54.1 kDa). This truncated enzyme form hydrolysed starch with aK
m of 3.845 mg/ml. Activity was optimal at pH 6.5 and 50°C, and the purified enzyme was stable at temperatures up to 50°C. While Hg2+, Fe3+ and Al3+ were effective in inhibiting the truncated enzyme Mn2+ and Co2+ considerably enhanced the activity. 相似文献
43.
44.
Ongoing studies show that what hitherto in Thailand and neighboring countries have been gathered under one variable species, Bulbophyllum lobbii , must be separated in a number of distinct, well defined species. One such. B. smitinandii , is treated here. 相似文献
45.
Gunnar Skarping Marianne Dalene 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1995,663(2)
Gas chromatography-mass spectrometry using chemical ionization with ammonia as reagent gas monitoring both positive and negative ions was applied. Negative-ion monitoring using ammonia and the pentafluoropropionic anhydride (PFPA) derivatives were chosen owing to low detection limits and good separation for the isomers studied. Technical-grade methylenediphenyldiioscyanate (MDI) was analysed and three isomers, 4,4′−, 2.4′− and 2,2−methylenediphenyldianiline (MDA), were determined in addition to methylated MDA. Plasma and urine from an exposed worker were hydrolysed and analysed and the MDA isomers were identified in the biological samples. 相似文献
46.
Antonio Balas Felix Garcia-Sanchez Fernando Gomez-Reino Jose L. Vicario 《Immunogenetics》1994,39(6):452-452
Correspondence to: J. L. Vicario. 相似文献
47.
Steffen Strcller Stanislaw Karpinski Jan-Erik Hällgren Gunnar Wingsle 《Physiologia plantarum》1994,92(3):443-450
A differential analysis of CuZn-superoxide dismutase (SOD. EC 1.15.1.1) isozymes after native-polyacry lamide gel elecrrophoresis (PAGE) and isoelectric focusing (IEF) indicated that germinating seeds of Scots pine (Pinus sylvestris L.) 3 days after the start of imbibition (3 DAI) contain five CuZn-SOD isozymes. Two isozymes co-migrated on native–PAGE but were separated after IEF. CuZn-SODs of Scots pine were purified from germinating seeds (3 DAI) by anion-exchange chromatography, hydrophobic interaction chromatography and chromatofocusing. The final separation of CuZn-SOD isozymes was accomplished by native-PAGE. CuZn-SOD isozymes were electroblotted and their NH2 -terminal amino acid sequence was determined. Comparisons of the amino acid sequences with sequences of CuZn-SOD isozymes from other plant sources indicated that one CuZn-SOD isozyme was of the chloroplastic type whereas the other four isozymes belonged to the cytosolic-type CuZn-SODs, The NH2 -terminal amino acid sequence of the chloroplastic CuZn-SOD and of one cytosolic-type CuZn-SOD were identical to those of two previously isolated, sequenced and localized CuZn-SOD isozymes from Scots pine needles. Two cytosolic-type CuZn-SOD isozymes showed a homology at 20 out of 21 NH2 -terminal amino acids. Mitochondria and glyoxysomes were isolated by differential and Percoll density-gradient centrifugation from germinating seeds (3 DAI). The cell fractionation experiments did not suggest that a major part of the CuZn-SOD activity in germinating seeds was derived from glyoxysomes or mitochondria. 相似文献
48.
High-temperature gas chromatography and gas chromatography-inass spectrometry for the analyses of oligosaccharides derived
from glycoproteins or glycosphingolipids has been developed. Pcrmethylatcd oligosaccharides with up to about 12 sugar residues
and masses up to 2500 Daltons can be analyzed. This approach is discussed and exemplified. 相似文献
49.
Xue-Fan Gu Felix de Rooij J. S. Lee Kor Te Velde Jean Charles Deybach Yves Nordmann Bernard Grandchamp 《Human genetics》1993,91(2):128-130
Acute intermittent porphyria (AIP) is an autosomal dominant disease characterized by a deficiency of porphobilinogen deaminase (PBGD). Up to now 14 different mutations have been described. In an effort to investigate the molecular epidemiology of AIP we have undertaken a systematic study of different exons of the PBGD gene from a large number of unrelated patients. Here, exon 8 from 82 unrelated Dutch and French AIP patients was examined using single strand confirmation polymorphism analysis (SSCP) after polymerase chain reaction (PCR) amplification. A single base mutation, C to T, at position 346 of the sequence coding for PBGD was observed in 15 Dutch families but in only 1 French family. A simple PCR assay is described to facilitate the diagnosis of this common mutation at the DNA level. 相似文献
50.
Bjørn-Yngvar Nordvåg Ida Ranløv Hilde Monica Frostad Riise Gunnar Husby M. Raafat El-Gewely 《Human genetics》1993,92(3):265-268
Severe familial amyloid cardiomyopathy (FAC) in a Danish kindred is associated with a specific mutation (Met for Leu 111) in the transthyretin (TTR) gene. The mutation causes the loss of a DdeI restriction site in the gene, allowing molecular diagnostic studies. We studied formalin-fixed, paraffin-embedded tissues, up to 39 years old, from 29 family members of this kindred. DNA was partially purified from deparaffinized tissue sections and a DNA sequence of the TTR gene flanking the mutation site was amplified by the polymerase chain reaction (PCR), followed by restriction enzyme analysis. Amplified DNA was obtained from tissues representing 23 of the 29 persons. Ten out of the 23 family members were found to carry the TTR Met 111 mutation, whereas 13 were not affected. The results were consistent with known clinical data and with corresponding serum TTR examinations. This retrospective study shows that archival tissues can be used to confirm the diagnosis and disease pattern in members of families affected by hereditary diseases. 相似文献