Fermentation of xylans by Butyrivibrio fibrisolvens and other ruminal bacteria

The ability of Butyrivibrio fibrisolvens and other ruminal bacteria (6 species, 18 strains) to ferment a crude xylan from wheat straw or to ferment xylans from larchwood or oat spelts was studied. Liquid cultures were monitored for carbohydrate utilization, cell growth (protein), and fermentation acid production. B. fibrisolvens 49, H17c, AcTF2, and D1 grew almost as well on one or more of the xylans as they did on cellobiose-maltose. B. fibrisolvens 12, R28, A38, X10C34, ARD22a, and X6C61 exhibited moderate growth on xylans. Partial fermentation of xylans was observed with Bacteroides ruminicola B14, Bacteroides succinogenes S85, Ruminococcus albus 7, Ruminococcus flavefaciens C94 and FD1, and Succinivibrio dextrinosolvens 22B. All xylans tested appeared to have a small fraction of carbohydrate that supported low levels of growth of nonxylanolytic strains such as Selenomonas ruminantium HD4. Compared to growth on hexoses, the same array of fermentation acids was produced upon growth on xylans for most strains; however, reduced lactate levels were observed for B. fibrisolvens 49 and Selenomonas ruminantium HD4. Measurements of enzyme activities of B. fibrisolvens AcTF2, 49, H17c, and D1 indicated that the xylobiase activities were cell associated and that the xylanase activities were predominantly associated with the culture fluid. The pattern of expression of these enzymes varied both between strains and between the carbon sources on which the strains were grown.     

Transfection of a DNA/protein complex into nuclei of mammalian cells using polyoma capsids and electroporation

We used empty capsids ofpolyoma virus to transfer DNA fragments and DNA/protein complexes into human cells. We encapsulated labeled and unlabeled single stranded DNA fragments by viral capsids. A complex of DNA with a DNA binding protein, recA, will also be taken up by the capsids, whereas the free protein is not incorporated. We further compared this gentle biological method of DNA transfection with a well-established physical method, electroporation. Electroporation also allows the transfer of DNA as well as protein into cells, although there is no proof that a DNA/protein complex can survive the procedure functionally. Whereas the viability of capsid transfected cells is unaffected (100%), electroporation reduces the viability to 90–95%. On the other hand, the amount of DNA found in the nucleus of electroporated cells is higher than for cells treated with loaded viral capsids.     

Turnover of Brain Monoamine Oxidase Measured In Vivo by Positron Emission Tomography Using l-[11C]Deprenyl

The distribution of carbon-11-labeled L-deprenyl, an irreversible inhibitor of monoamine oxidase type B (MAO-B), was determined in the baboon brain by positron emission tomography. The irreversible blood-to-brain transfer constant (influx constant, K_i) was measured using a complete metabolite-corrected arterial plasma concentration curve. This influx constant was used as a measure of functional enzyme activity for sequential determinations of MAO-B recovery following a single high dose of unlabeled l -deprenyl. The half-life for turnover of MAO-B was thus determined to be 30 days. Using appropriate irreversible inhibitors, this procedure should be generally useful for determining enzyme turnover rates in any organ in vivo and can be applied to some human studies as well.     

Risk of AIDS related complex and AIDS in homosexual men with persistent HIV antigenaemia.

One hundred and ninety eight men seropositive for human immunodeficiency virus (HIV) antibody and 58 HIV antibody seroconverters were studied for an average of 19.3 (SEM 0.5) months to assess the relation between HIV antigenaemia and the risk of developing the acquired immune deficiency syndrome (AIDS) and AIDS related complex. Forty (20.2%) of the 198 HIV antibody seropositive men were antigen positive at entry and remained so during follow up. Eight (13.8%) of the 58 HIV antibody seroconverters and 20 (12.7%) of the remaining 158 HIV antibody seropositive men became antigen positive during follow up, resulting in an end point attack rate for HIV antigenaemia of 14.3%. AIDS related complex was diagnosed in 25 (15.8%) of the HIV antigen negative men and in 14 (20.7%) of the HIV antigen positive men. AIDS was diagnosed in 15 men, resulting in an end point attack rate for AIDS of 23.9% in the HIV antigen positive group and 1.3% in the antigen negative group. HIV antibody seropositive men without symptoms but with persistent HIV antigenaemia are at increased risk of developing AIDS and AIDS related complex.     

Method for rapid separation of 3,5,3'-triiodothyroacetic acid in human serum by fast protein liquid chromatography

The 3,5,3'-triiodothyroacetic acid (TRIAC) has been approved as a valuable agent in the management of hyperthyroidism secondary to inappropriate secretion of thyrotropin. We have developed a fast protein liquid chromatography (FPLC) method for separation and quantification of TRIAC. Serum samples charged with TRIAC were extracted with methanol/ammonium acetate, the supernatants were evaporated to dryness, reconstituted in NaOH and injected on a reversed phase column for chromatography. For separation an isocratic elution method (methanol water; 0.1% trifluoroacetic acid) was used. The area under the curve (ml%) was compared with those of the calibration curves. Recoveries were 70 +/- 10.8%. TRIAC was eluted in 2.33 ml. Conclusively, the present method shows that TRIAC can be measured by FPLC and may be applied to the measurement of TRIAC in pharmacological studies.     

BglII restriction fragment length polymorphisms at the human p53 gene locus

Summary A new restriction fragment length polymorphism detected with the restriction endonuclease BglII (AGATCT) is presented.     

Transformation with a mutant Arabidopsis acetolactate synthase gene renders tobacco resistant to sulfonylurea herbicides

Summary A gene encoding acetolactate synthase was cloned from a chlorsulfuron-resistant mutant of Arabidopsis. The DNA sequence of the mutant gene differed from that of the wild type by a single base pair substitution. When introduced into tobacco by Ti plasmid-mediated transformation the gene conferred a high level of herbicide resistance. These results suggest that the cloned gene may confer agronomically useful levels of herbicide resistnace in other crop species, and that it may be useful as a selectable marker for plant transformation experiments.