High mobility group nonhistone chromosomal proteins also exist in Tetrahymena.

High mobility group (HMG) nonhistone chromosomal proteins have been shown to exist also in the ciliated protozoan Tetrahymena pyriformis. One or two histone-like components were extracted with 0.25 M HCl from the chromatin, in addition to five histone species. These proteins were also extracted selectively with 0.5 M HClO4, 0.35 M NaCl, or 4 mM spermidine, together with H1 histone, and were characterized as HMG proteins on the basis of the following criteria: high mobilities on polyacrylamide gel electrophoresis, relatively low molecular weights, amino acid compositions rich in lysine and glutamic acid, and relative contents in chromatin. This extends the distribution of the HMG proteins to all four eukaryotic kingdoms, and suggests the possibility that they have some universal role in chromatin structure and function.     

Identification of suberimidate cross-linking sites of four histone sequences in H1-depleted chromatin. Histone arrangement in nucleosome core

The arrangement of 8 histones in the nucleosome core has been investigated by identifying the sites of 4 histone sequences cross-linked with a bifunctional amino-group reagent, dimethyl suberimidate, selected from among 4 diimidoesters of various linker lengths examined. H1-depleted calf thymus chromatin was allowed to react with 14C-labeled suberimidate at pH 8.5 and 0 degrees C. The cross-linked chromatin was then digested exhaustively with trypsin. Almost all the histone fragments were released from the chromatin with 0.25 M HCl and chromatographed on several columns and on paper. Cross-linked peptides were detected by analyzing the content of radioactive suberimidoylbislysine after acid hydrolysis. The chromatographic procedure developed here showed that the whole histone fragments contained 29 mol% of the total linked reagent as suberimidoylbisylsine. The 5 finally purified cross-linked peptides were identified from the total and N-terminal amino acids of each pair of peptides separated by two-dimensional cellulose thin layer chromatography after cutting the linker by ammonolysis. Thus, intramolecular cross-linking was found between Lys-5 and Lys-9 of H2A, and Lys-34 and Lys-85 of H2B, while intermolecular cross-linking was found between Lys-24 (or 27) of H2B and Lys-74 of H2A, Lys-85 of H2B and Lys-91 of H4, and Lys-120 of H2B and Lys-115 of H3 and/or Lys-77 of H4. Most of these lysine residues are located in the DNA-binding segments of the 4 histone sequences identified previously [Kato, Y. & Iwai, K, (1977) J. Biochem. 81, 621--630]. All the 5 or 6 cross-links can be located in a heterotypic tetramer consisting of one molecule each of H2A, H2B, H3, and H4, and a model of the histone arrangement in the tetramer is proposed. Two such tetramers may compose to the histone octamer in the nucleosome core.     

Tremorgenic Mycotoxin from Penicillium paraherquei

A tremorgenic mycotoxin was isolated from Penicillium paraherquei Abe ex G. Smith and identified as verruculogen. It was produced at the rate of approximately 1 mg/g of the dried fungal mycelium cultured on peptone-enriched Czapek-Dox medium at 28°C.     

Studies on the sites in histones phosphorylated by adenosine 3':5'-monophosphate-dependent and guanosine 3':5'-monophosphate-dependent protein kinases.

Adenosine 3':5'-monophosphate-dependent protein kinase (protein kinase A) purified from silkworm pupae phosphorylated five major fractions of calf thymus histone, whereas guanosine 3':5'-monophosphate-dependent protein kinase (protein kinase G) purified from the same organism reacted preferentially with H1, H2A, and H2B histones. Amino acid analysis of the phosphopeptides which were obtained by proteolytic digestion revealed that both protein kinases A and G showed the abilities to phosphorylate the same serine hydroxyl groups in H1 and H2B histones. Both protein kinases reacted with Ser-38 in H1 histone. With H2B histone as substrate protein kinase A phosphorylated Ser-32 as well as Ser-36, whereas protein kinase G reacted preferentially with Ser-32 and the reaction with Ser-36 was very slow. H3 and H4 histones were practically inactive substrates for protein kinase G. Although H2A histone has not been analyzed, the evidence has raised a possibility that protein kinase G utilizes a portion of the substrate proteins for protein kinase A.     

Kinetics of proton transfer reactions of lysozyme with p-nitrophenol near neutral pH—a study of dynamic properties of Glu 35 and His 15

Kinetics of proton transfer between lysozyme and a pH indicator p-nitrophenol (p-Np) were measured by the temperature-jump method in a pH range of 6.0–7.0. Two well-defined relaxation processes were observed. The fast process (τ ? 15 μsec) was also observed for a lysozyme derivative succinylated at the terminal α-amino group of Lys 1. Therefore, the fast process was found to be attributable to the proton transfer reaction of His 15 with p-Np. The slow process (τ ? 50 μsec) was found to be characteristic of the proton transfer reaction of Glu 35, because it disappeared completely in solution containing a lysozyme derivative having an ester crosslink between the carboxyl group of Glu 35 and indol C-2 of Trp 108. The rate constants for proton transfer from Glu 35 and His 15 to p-Np were found to be 9 × 10⁶/sec/M (±65%, 23°C) and 3 × 10⁸/sec/M (±20%, 25°C), respectively. These data indicate that the proton of the carboxyl group of Glu 35 is kinetically stabilized in lysozyme.     

Regulation of the expression of the rat angiotensin II receptor mRNA.

Regulation of the expression levels of the rat angiotensin II receptor mRNA in the adrenal, aorta, kidney, and brain was assessed by the competitive polymerase chain reaction method. The bilateral nephrectomy or the administration of Dup753 markedly reduced the expression levels of this receptor mRNA in the adrenal and brain stem, but not in the kidney nor aorta. A continuous infusion of angiotensin II increased the expression level of this receptor mRNA in the adrenal but not in the other tissues. It is suggested that the expression level of this receptor mRNA in the adrenal is dependent on the renin angiotensin aldosterone system.     

Virtual issue: cell wall functions in plant growth and environmental responses

Journal of Plant Research - Plant cell walls have multiple functions, including determining cell shape and size, cell–cell adhesion, controlling cell differentiation and growth, and promoting...     

Effect of Caffeine-Containing Beverage Consumption on Serum Alanine Aminotransferase Levels in Patients with Chronic Hepatitis C Virus Infection: A Hospital-Based Cohort Study

Introduction

To date, there have been no prospective studies examining the effect of coffee consumption on serum alanine aminotransferase (ALT) level among individuals infected with the hepatitis C virus (HCV). We conducted a hospital-based cohort study among patients with chronic HCV infection to assess an association between baseline coffee consumption and subsequent ALT levels for 12 months.

Materials and Methods

From 1 August 2005 to 31 July 2006, total 376 HCV-RNA positive patients were recruited. A baseline questionnaire elicited information on the frequency of coffee consumption and other caffeine-containing beverages. ALT level as a study outcome was followed through the patients’ medical records during 12 months. The association between baseline beverage consumption and subsequent ALT levels was evaluated separately among patients with baseline ALT levels within normal range (≤45 IU/L) and among those with higher ALT levels (>45 IU/L).

Results

Among 229 patients with baseline ALT levels within normal range, 186 (81%) retained normal ALT levels at 12 months after recruitment. Daily drinkers of filtered coffee were three times more likely to preserve a normal ALT level than non-drinkers (OR=2.74; P=0.037). However, decaffeinated coffee drinkers had a somewhat inverse effect for sustained normal ALT levels, with marginal significance (OR=0.26; P=0.076). In addition, among 147 patients with higher baseline ALT levels, 39 patients (27%) had ALT reductions of ≥20 IU/L at 12 months after recruitment. Daily drinkers of filtered coffee had a significantly increased OR for ALT reduction (OR=3.79; P=0.034). However, in decaffeinated coffee drinkers, OR could not be calculated because no patients had ALT reduction.

Conclusion

Among patients with chronic HCV infection, daily consumption of filtered coffee may have a beneficial effect on the stabilization of ALT levels.     

Population genetic structure in a threatened tree, Pyrus calleryana var. dimorphophylla revealed by chloroplast DNA and nuclear SSR locus polymorphisms

Pyrus calleryana var. dimorphophylla, a variety of Callery pear (Pyrus calleryana), is endemic to the Tokai district of central Japan, and is currently listed as “Endangered”. The remnant habitats and trees are of limited number, and highly fragmented. As the first step in determining appropriate conservation units, genetic diversity and differentiation in this species were investigated using chloroplast DNA (cpDNA) and nuclear simple sequence repeat (SSR) polymorphisms. All possible remnant trees were genotyped, then six populations were defined based on the results of cpDNA haplotype determination and Bayesian clustering approaches performed using the SSR locus data. Some trees appeared to originate from artificial propagation. Some individuals were difficult to differentiate genetically from the related species, Pyrus × uyematsuana, which is considered to be a hybrid between P. calleryana var. dimorphophylla and a possibly naturalized species, Pyrus pyrifolia, implying that introgression between these species may have occurred. In P. calleryana var. dimorphophylla, anthropogenic factors such as propagation and related species planting are probably major causes of complexity in the genetic structure.