Temperature-dependent splicing of beta-globin pre-mRNA

A T→G mutation at nucleotide 705 of human β-globin intron 2 creates an aberrant 5′ splice site and activates a cryptic 3′ splice site upstream. In consequence, the pre-mRNA is spliced via aberrant splice sites, despite the presence of the still functional correct sites. Surprisingly, when IVS2-705 HeLa or K562 cells were cultured at temperatures below 30°C, aberrant splicing was inhibited and correct splicing was restored. Similar temperature effects were seen for another β-globin pre-mRNA, IVS2-745, and in a construct in which a β-globin intron was inserted into a coding sequence of EGFP. Temperature-induced alternative splicing was affected by the nature of the internal aberrant splice sites flanking the correct sites and by exonic sequences. The results indicate that in the context of thalassemic splicing mutations and possibly in other alternatively spliced pre-mRNAs, temperature is one of the parameters that affect splice site selection.     

The use of tri-O-acetyl-D-glucal and -D-galactal in the synthesis of 3-acetamido-2,3-dideoxyhexopyranoses and -hexopyranosides

Addition of hydrazoic acid to alpha,beta-unsaturated aldehydes derived from tri-O-acetyl-D-glucal and -D-galactal gave 3-azido-2,3-dideoxyhexopyranoses. These were converted into 1,4,6-tri-O-acetyl-3-azido-2,3-dideoxyhexopyranoses as well as methyl and ethyl glycosides. Hydrogenation of the proamine group in 3-azido-2,3-dideoxy derivatives provided different 3-amino and 3-acetamido sugars. The configuration and conformation of all products were established on the basis of the 1H and 13 C NMR, IR and polarimetric data.     

Characteristics of arylsulfatase in Russian sturgeon (Acipenser gueldenstaedti) semen

Spermatozoa of sturgeons (Acipenseriformes), unlike teleosts, possess an acrosome. This paper provides data concerning biochemical characteristics of arylsulfatase (AS), an acrosomal enzyme, found in Russian sturgeon spermatozoa and seminal plasma. The enzymes were purified by a four-step procedure, using n-butanol extraction, ion-exchange chromatography repeated twice and gel filtration. High purity of our enzymes was confirmed by silver staining electrophoresis and an immunological experiment. Kinetic parameters indicated that the purified enzymes belong to arylsulfatase type A. Similarity of the seminal plasma arylsulfatase to the spermatozoan enzyme showed us that arylsulfatase from seminal plasma might originate from damaged spermatozoa. The possible physiological consequences of the presence of arylsulfatase in Russian sturgeon semen are discussed.     

Serological characterization of anti-endotoxin serum directed against the conjugate of oligosaccharide core of Escherichia coli type R4 with tetanus toxoid

The covalent conjugate of oligosaccharide core of Escherichia coli type R4 with tetanus toxoid was prepared using reaction of reductive amination. The neoglycoconjugate was a good immunogen in rabbits yielding a high level of anti-lipopolysaccharide (LPS) antibodies of the IgG class. It was found that antiserum was able to react with the smooth LPS molecules of identical (R4) or related (R1) core type. The reactions were shown in the enzyme-linked immunosorbent assay and the immunoblotting test. Flow cytometry showed that anti-core antibodies reacted with LPS present on intact, live, smooth bacteria labelling more than 90% of cells. The anti-OS R4-TT serum used for in vitro studies showed high endotoxin neutralization activity. The serum inhibited endotoxin-induced tumor necrosis factor alpha and nitric oxide synthesis by the J-774A.1 cell line and attenuated pulmonary retention of YAC-1 cells.     

Molecular detection of Megatrypanum trypanosomes in tabanid flies

Trypanosomes of the subgenus Megatrypanum have been isolated from many mammalian hosts around the world. They are usually non-pathogenic, although they may confuse the parasitological diagnosis of trypanosomosis. Additionally, Trypanosoma theileri has been associated with disease in cattle. Megatrypanum trypanosomes are considered to be transmitted by different arthropods, including tabanids. However, little is known about the potential vectors of Megatrypanum trypanosomes in different parts of the world. The present study reports on the detection of Megatrypanum trypanosomes in Heamatopota pluvialis, Tabanus bromius, Tabanus maculicornis and Tabanus distinguendus in Poland. It also discusses the possible role of these tabanids in the transmission of Megatrypanum trypanosomes.     

Target selection and determination of function in structural genomics

The first crucial step in any structural genomics project is the selection and prioritization of target proteins for structure determination. There may be a number of selection criteria to be satisfied, including that the proteins have novel folds, that they be representatives of large families for which no structure is known, and so on. The better the selection at this stage, the greater is the value of the structures obtained at the end of the experimental process. This value can be further enhanced once the protein structures have been solved if the functions of the given proteins can also be determined. Here we describe the methods used at either end of the experimental process: firstly, sensitive sequence comparison techniques for selecting a high-quality list of target proteins, and secondly the various computational methods that can be applied to the eventual 3D structures to determine the most likely biochemical function of the proteins in question.     

The structure of the littoral: effects of waterlily density and perch predation on sediment and plant‐associated macroinvertebrate communities

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Metabolism of phenolic compounds in <Emphasis Type="Italic">Vitis riparia</Emphasis> seeds during stratification and during germination under optimal and low temperature stress conditions

We studied the alterations in phenolic compounds in grape seeds during their stratification and germination under optimal conditions (+25 °C) and at low temperature (+10 °C). Biological materials in the study were seeds of Vitis riparia. Phenolic compounds were extracted from defatted seeds using 80 % methanol or 80 % acetone. The content of total phenolics was determined with the Folin-Ciocalteau reagent, while the content of tannins was determined by vanillin assay and the protein (BSA) precipitation method. The RP-HPLC method was used to determine phenolic compounds (phenolic acids, catechins) in the extracts. High amounts of tannins, catechins, gallic acid and lesser amounts of p-coumaric acid were found in the seeds. The content of total phenolics in acetone extracts was higher than that obtained using methanol. The amounts of phenolic acids and tannins found in V. riparia seeds after stratification were much lower. It may confirm a possible role of these compounds in dormancy of V. riparia seeds. After 72 h of low temperature treatment, inhibition of grape root growth and biochemical changes in seeds were detected. The chilling stimulated increased accumulation of some phenolic compounds (free gallic acid and catechins) in the seeds. These substances can protect plants against some abiotic stressors.