Fermentation of barley straw by anaerobic rumen bacteria and fungi in axenic culture and in co-culture with methanogens

When incubated in axenic culture, strains of anaerobic rumen fungi were more active than cellulolytic bacteria in solubilizing barley straw stem fragments 5 to 10 mm in length. Pretreatment with ammonia had little effect on microbial attack. Of three species of methanogens tested, Methanobrevibacter smithii strain PS formed the most stable and reproducible co-cultures with the fungi and with Ruminococcus albus , and the presence of this organism enhanced the extent of degradation of straw, although this effect was less marked than that previously observed when pure cellulose was used as substrate.     

Identification of a cysteine residue at the active site of Escherichia coli isocitrate lyase.

Escherichia coli isocitrate lyase was inactivated by iodacetate in a pseudo-first-order process. Complete inactivation was associated with the incorporation of only one carboxymethyl group per enzyme subunit. The substrate and products of the enzyme protected against inactivation, suggesting that the reactive group may be located at the active site. Isolation and sequencing of a carboxymethylated peptide showed that the modified residue was a cysteine, in the sequence Cys-Gly-His-Met-Gly-Gly-Lys. The reactivity of isocitrate lyase to iodoacetate declined with pH, following a titration curve for a group of pKa 7.1. The Km of the enzyme for isocritrate declined over the same pH range.     

Identification of a novel metabolite in phenanthrene metabolism by the fungus Cunninghamella elegans

The metabolism of phenanthrene by the fungus Cunninghamella elegans was investigated. Kinetic experiments using [9-14C]phenanthrene showed that after 72 h, 53% of the total radioactivity was associated with a glucoside conjugate of 1-hydroxyphenanthrene (phenanthrene 1-O-beta-glucose). This metabolite was isolated by reversed-phase high-performance liquid chromatography and characterized by the application of UV absorption, 1H nuclear magnetic resonance, and mass spectral techniques. The results show that aromatic ring oxidation followed by glucosylation is a predominant pathway in the metabolism of the polycyclic aromatic hydrocarbon phenanthrene by C. elegans.     

The chalcone synthase multigene family of Petunia hybrida (V30): differential,light-regulated expression during flower development and UV light induction

We have analysed the expression of the 8–10 members of the gene family encoding the flavonoid biosynthetic enzyme chalcone synthase (CHS) from Petunia hybrida. During normal plant development only two members of the gene family (CHS-A and CHS-J) are expressed. Their expression is restricted to floral tissues mainly. About 90% of the total CHS mRNA pool is transcribed from CHS-A, wheares CHS-J delivers about 10% in flower corolla, tube and anthers. Expression of CHS-A and CHS-J during flower development is coordinated and (red) light-dependent. In young seedlings and cell suspension cultures expression of CHS-A and CHS-J can be induced with UV light. In addition to CHS-A and CHS-J, expression of another two CHS genes (CHS-B and CHS-G) is induced in young seedlings by UV light, albeit at a low level. In contrast to CHS genes from Leguminoseae, Petunia CHS genes are not inducible by phytopathogen-derived elicitors. Expression of CHS-A and CHS-J is reduced to a similar extent in a regulatory CHS mutant, Petunia hybrida Red Star, suggesting that both genes are regulated by the same trans-acting factors. Comparison of the promoter sequences of CHS-A and CHS-J reveals some striking homologies, which might represent cis-acting regulatory sequences.     

Variance within homogeneous phytoplankton populations, I: Theoretical framework for interpreting histograms

A framework is presented for interpreting frequency distributions of volume or fluorescence as measured by a flow cytometer on homogeneous phytoplankton populations. The framework, based on both laboratory experience and theoretical concepts, is illustrated with the use of a simulation model. Asynchronous, synchronous, and phased populations were simulated, with constant and variable growth patterns over the cell cycle. Though simulations produced a wide variety of histogram shapes, including multimodal distributions, the primary difference between asynchronous and synchronous/phased distributions lies in their temporal variation. Histograms that are constant in time indicate asynchronous populations; when populations are not asynchronous, their histogram shapes vary with a periodicity on the same time scale as the cell cycle. A probability density function for the case of asynchronous populations with a constant growth rate is derived. When fitted to simulated histograms this two-parameter density function yields estimates of the two parameters: mean and variance of cell volume (or mass) at age 0.     

RAMARIA SUBGENERA RAMARIA AND LAETICOLORA IN YUNNAN

Three taxa of Ramaria subgenus Ramaria, and 18 of subg. Laeticolora are reported from Yunnan Province. Of these 13 are considered new to science. Only one taxon (R. formosa) is considered of widespread distribution, the others being known olay from the Indo-Asian subcontinent. Wide distribution patterns, based on phenetic similarity, seem to be at the infraspecific to species complex level, but only rarely contaxie. New taxa are as follows: subg. Ramaria: R. eryuanensis; subg. Laeticolora: R. brunneipes, R. distinctissima, R. ephemeroderma, R. hilaris, R. lacviformosoides, R. linearioides, R. linearis, R. nanispora, R. rubri-attenuipcs, R. sino-conjunctipes, R. rubricarnata var. laeta, R. botrytoides var. microspora, and R. neoformosa var. sinensis. Keys to Yunnan taxa of Ramaria subgenera Ramarla and Laeticolora are furnished.     

A Freeze-Sectioning Method for Preparation of the Detergent-Resistant Cytoskeleton Identifies Stage-Specific Cytoskeleal Proteins and Associated mRNA in Xenopus Oocytes and Embryos

Proteins of the detergent-resistant cytoskeleton fraction and the detergent-soluble fraction from Xenopus oocytes and embryos are examined using a procedure which allows rapid and uniform extraction of tissues and large, single cells. SDS-polyacrylamide gels reveal only a few prominent cytoskeletal proteins in the early embryo, however qualitatively different proteins begin to appear after gastrulation. Incorporation of [³⁵S]-methionine into newly synthesized proteins indicates that there is synthesis and assembly of proteins into the cytoskeleton, but the amount remains low until after gastrulation. The use of nucleic acid probes for alpha-tubulin and actin mRNA indicates that about 80% of these mRNAs in the oocyte and meiotically mature egg are bound to the detergent-resistant cytoskeleton.     

Phosphorylation of bovine hormone-sensitive lipase by the AMP-activated protein kinase. A possible antilipolytic mechanism

Hormone-sensitive lipase is phosphorylated at a single site (site 2) in vitro by the AMP-activated protein kinase, without any direct effect on the activity of the enzyme. The amino acid sequence around this site has been determined. Ca2+/calmodulin-dependent protein kinase II also phosphorylates hormone-sensitive lipase predominantly at this site, whilst cyclic-GMP-dependent protein kinase phosphorylates exclusively the regulatory site (site 1) which is also phosphorylated by cyclic-AMP-dependent protein kinase. Phosphorylation of site 2 has been found to inhibit subsequent phosphorylation and activation of hormone-sensitive lipase by the cyclic-AMP-dependent and cyclic-GMP-dependent protein kinases, indicating that site-2 phosphorylation may have an antilipolytic role in vivo.     

Translational regulation of ferritin synthesis in rat spleen: effects of iron and inflammation

Translational control of ferritin synthesis was studied in rat spleen, and compared with that for liver, heart and brain, in response to iron and inflammation. Spleen concentrations of total RNA in the ribonucleoprotein (mRNP) fraction was comparable to that for liver, while polyribosomal RNA was less. Both fractions were ten-fold lower in heart and brain. In untreated animals, the mRNP fraction of all tissues had the largest portion of the ferritin mRNA, as determined by slot blot hybridization with 32P-labeled cDNA for the L subunit. Acute treatment with ferric ammonium citrate shifted the spleen ferritin mRNA to the polyribosome fraction. This was also so in liver but not in the heart and brain which took up much less iron. The findings were confirmed by hybridization studies of mRNPs and polyribosomes separated in sucrose gradients. Turpentine-induced inflammation also caused a shift in ferritin mRNA from the mRNP to the polyribosome fraction of spleen and liver, over 12 h. We conclude that as in liver, spleen ferritin synthesis is under translational control by iron, and that both tissues also respond to inflammation by shifting of ferritin mRNA to the polyribosomes.