Formate-producing capacity provided by reducing ability of Streptococcus thermophilus nicotinamide adenine dinucleotide oxidase determines yogurt acidification rate

Yogurt is made by fermenting milk with 2 lactic acid bacteria, Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus. To comprehensively understand the protocooperation mechanism between S. thermophilus and L. bulgaricus in yogurt fermentation, we examined 24 combinations of cocultures comprising 7 fast- or slow-acidifying S. thermophilus strains with 6 fast- or slow-acidifying L. bulgaricus strains. Furthermore, 3 NADH oxidase (Nox)-deficient mutants (Δnox) and one pyruvate formate-lyase deficient mutant (ΔpflB) of S. thermophilus were used to evaluate the factor that determines the acidification rate of S. thermophilus. The results revealed that the acidification rate of S. thermophilus monoculture determined the yogurt fermentation rates, despite the coexistence of L. bulgaricus, whose acidification rate was either fast or slow. Significant correlation was found between the acidification rate of S. thermophilus monoculture and the amount of formate production. Result using ΔpflB showed that the formate was indispensable for the acidification of S. thermophilus. Moreover, results of the Δnox experiments revealed that formate production required Nox activity, which not only regulated dissolved oxygen, but also the redox potential. The Nox provided the large decrease in redox potential required by pyruvate formate-lyase to produce formate. A highly significant correlation was found between formate accumulation and Nox activity in S. thermophilus. In conclusion, the formate production ability provided by the action of Nox activity determines the acidification rate of S. thermophilus, and consequently, regulates yogurt coculture fermentation.

Rice (Oryza sativa) contains a novel isoform of glutamate decarboxylase that lacks an authentic calmodulin-binding domain at the C-terminus

We have isolated full-length cDNAs for two distinct isoforms of glutamate decarboxylase (GAD), designated OsGAD1 and OsGAD2 from a rice shoot cDNA library. Open reading frames found in OsGAD1 and OsGAD2 cDNAs encode putative proteins of 501 (56.7 kDa) and 500 amino acids (55.6 kDa), respectively. They show 69% identity to each other and 67-78% identity to dicotyledonous counterpart sequences determined so far. Comparative analysis of relevant genomic clones obtained from the rice genomic library with these cDNAs as probes demonstrated that the number and sizes of introns deduced for these two genes differ considerably. Interestingly, in the regions in the putative gene products corresponding to the C-terminal 30-amino-acid peptide known as the calmodulin-binding domain of plant GADs, OsGAD1 possesses a typical motif, while OsGAD2 contains several substitutions of amino acids that contribute strongly to the binding of calmodulin (CaM). An in vitro CaM-binding assay of these proteins over-expressed in Escherichia coli revealed that OsGAD1 can in fact bind specifically to bovine CaM but OsGAD2 cannot. RNA analysis showed that transcripts of OsGAD1 and OsGAD2 were present in all tissues examined, but their expression was differentially regulated, at least in roots and maturing seeds.

A tobacco nuclear extract supporting transcription, processing, splicing and modification of plant intron-containing tRNA precursors

Nuclear tRNA genes are transcribed by RNA polymerase III (Pol III) and pre-tRNAs are processed into mature tRNAs via complex processes in the nucleus. We have developed an in vitro Pol III-dependent transcription system derived from tobacco cultured cells, which supports efficiently not only transcription of a variety of plant tRNA genes but also 5'-and 3'-end processing, nucleotide modification and splicing of intron-containing pre-tRNAs. The structures of in vitro transcripts have been confirmed by primer extension analysis and by RNase T1 fingerprinting. The optimal Mg2+ concentration differed for each step so that each reaction can be controlled by adjusting the Mg2+ concentration. At 1 mm Mg2+, only transcription occurs so that pre-tRNAs accumulate. The splicing reaction can be initiated by raising Mg2+ ions (> 5 mm) and enhanced by adding 1 mm hexamminecobalt chloride. Using the optimized system for the Nicotiana intron-containing tRNATyr gene, the precise initiation and termination sites of transcription and the splice sites were determined. The presence of 1 mm NAD+ in the reaction mixture leads to the removal of the 2' phosphate at the splice junction of tRNATyr, demonstrating the activity of a 2'-phosphotransferase in the tobacco nuclear extract. Many modified nucleosides such as m2G, m22G, m1A, phi27 and phi35 are introduced in either of the studied transcripts. As shown in other systems, the conversion of U35 to phi requires an intron-containing substrate.

Tracking the estrogen receptor in neurons: implications for estrogen-induced synapse formation

Estrogens (E) and progestins regulate synaptogenesis in the CA1 region of the dorsal hippocampus during the estrous cycle of the female rat, and the functional consequences include changes in neurotransmission and memory. Synapse formation has been demonstrated by using the Golgi technique, dye filling of cells, electron microscopy, and radioimmunocytochemistry. N-methyl-d-aspartate (NMDA) receptor activation is required, and inhibitory interneurons play a pivotal role as they express nuclear estrogen receptor alpha (ERalpha) and show E-induced decreases of GABAergic activity. Although global decreases in inhibitory tone may be important, a more local role for E in CA1 neurons seems likely. The rat hippocampus expresses both ERalpha and ERbeta mRNA. At the light microscopic level, autoradiography shows cell nuclear [3H]estrogen and [125I]estrogen uptake according to a distribution that primarily reflects the localization of ERalpha-immunoreactive interneurons in the hippocampus. However, recent ultrastructural studies have revealed extranuclear ERalpha immunoreactivity (IR) within select dendritic spines on hippocampal principal cells, axon terminals, and glial processes, localizations that would not be detectable by using standard light microscopic methods. Based on recent studies showing that both types of ER are expressed in a form that activates second messenger systems, these findings support a testable model in which local, non-genomic regulation by estrogen participates along with genomic actions of estrogens in the regulation of synapse formation.

EXAFS analysis of the zinc-binding domain of boar spermatidal transition protein 2

Boar Spermatidal Transition Protein 2 (TP2; 137 amino acid residues) is supposed to play an important role in initiation of chromatin condensation and cessation of transcriptional activity during mammalian spermniogenesis. Boar TP2 has three potential zinc finger motifs and binds three atoms of zinc per molecule. However the structure of the zinc-binding domain of boar TP2 has not been completely determined. To elucidate the local structure around the zinc atoms of boar TP2, we performed an X-ray absorption fine structure (XAFS) measurement on the zinc-binding domain of TP2(TP2Z)(residues 1-103) in the fluorescence mode. By EXAFS analyses we have demonstrated that each of the three zinc atoms is coordinated by approximately two sulfur and two nitrogen atoms on average. The average Zn-S and Zn-N distances were found to be 2.36 and 2.01 A, respectively. The sulfur and nitrogen atoms are attributed to cysteine and histidine residues, respectively, from comparison of the EXAFS spectra with model compounds ZnS and ZnTPP zinc(II) tetraphenylporphyrin).

Protamine dissociation before decondensation of sperm nuclei during in vitro fertilization of pig oocytes

The correlation between morphological changes and the dynamics of protamine in boar sperm chromatin during in vitro fertilization of pig oocytes matured in vitro was assessed. For this purpose, protamine was purified from boar sperm nuclei and an antiserum against protamine was developed. After affinity purification, the antiserum reacted exclusively with boar protamine during western blotting, showing no crossreactivity with core histones. Immunohistochemical evaluation revealed that only fully developed spermatid nuclei in boar testes stained strongly with the antiserum. When pig oocytes matured in vitro were fertilized in vitro, sperm penetration was observed in 37% of oocytes at 2 h after insemination and the penetration rate increased to 99% by 5 h after insemination, accompanied by an increase in polyspermic penetration. Paraffin wax sections of the inseminated oocytes were examined by immunohistochemical analysis with the antiserum. The proportion of condensed sperm nuclei that reacted with the antiserum was 87% of the sperm nuclei that penetrated by 2 h after insemination, and this decreased to 20 and 13% at 3 and 5 h after insemination, respectively. However, none of the decondensing sperm nuclei or male pronuclei reacted with the antiserum during the entire insemination period. These results indicate that a specific antiserum against boar protamine can be raised and, using this serum, it has been demonstrated that protamine is dissociated from boar sperm nuclei before decondensation during in vitro fertilization.

Protamine dissociation before decondensation of sperm nuclei during in vitro fertilization of pig oocytes

The correlation between morphological changes and the dynamics of protamine in boar sperm chromatin during in vitro fertilization of pig oocytes matured in vitro was assessed. For this purpose, protamine was purified from boar sperm nuclei and an antiserum against protamine was developed. After affinity purification, the antiserum reacted exclusively with boar protamine during western blotting, showing no crossreactivity with core histones. Immunohistochemical evaluation revealed that only fully developed spermatid nuclei in boar testes stained strongly with the antiserum. When pig oocytes matured in vitro were fertilized in vitro, sperm penetration was observed in 37% of oocytes at 2 h after insemination and the penetration rate increased to 99% by 5 h after insemination, accompanied by an increase in polyspermic penetration. Paraffin wax sections of the inseminated oocytes were examined by immunohistochemical analysis with the antiserum. The proportion of condensed sperm nuclei that reacted with the antiserum was 87% of the sperm nuclei that penetrated by 2 h after insemination, and this decreased to 20 and 13% at 3 and 5 h after insemination, respectively. However, none of the decondensing sperm nuclei or male pronuclei reacted with the antiserum during the entire insemination period. These results indicate that a specific antiserum against boar protamine can be raised and, using this serum, it has been demonstrated that protamine is dissociated from boar sperm nuclei before decondensation during in vitro fertilization.

Identification of two catalytic subunits of tRNA splicing endonuclease from Arabidopsis thaliana

tRNA splicing endonuclease is essential for the correct removal of introns from precursor tRNA molecules of Archaea and Eucarya. The only well-characterized eucaryotic enzyme until now is the endonuclease from yeast (Saccharomyces cerevisiae). This protein has a heterotetrameric structure. Two of the four subunits, i.e. Sen34 and Sen44, contain the active sites for cleavage at the 3'- and 5'-splice sites, respectively. We have identified three novel genes from Arabidopsis thaliana, encoding putative subunits of tRNA splicing endonuclease. They are designated as AtSen1, AtSen2, and AtpsSen1. Both genes AtSen1 and AtSen2 seem to be functionally active, as deduced from corresponding cDNA sequences. Comparison of the amino acid sequences of the these two Arabidopsis proteins revealed 72% identity. However, AtpsSen1 is more similar to AtSen1, but is very likely a pseudogene, as concluded from extended stretches of deletions and the presence of in-frame stop codons. All putative proteins contain a conserved domain at their C-terminus common to counterparts from other organisms. Interestingly, they are more similar to the yeast catalytic subunit Sen44 than to Sen34. Southern analysis with various probes revealed that each gene is present as single copies in the nuclear genome. The evolutionary implications of these findings are discussed.

Splicing of arabidopsis tRNA(Met) precursors in tobacco cell and wheat germ extracts

Intron-containing tRNA genes are exceptional within nuclear plant genomes. It appears that merely two tRNA gene families coding for tRNA(GpsiA(Tyr)) and elongator tRNA(CmAU(Met)) contain intervening sequences. We have previously investigated the features required by wheat germ splicing endonuclease for efficient and accurate intron excision from Arabidopsis pre-tRNA(Tyr). Here we have studied the expression of an Arabidopsis elongator tRNA(Met) gene in two plant extracts of different origin. This gene was first transcribed either in HeLa or in tobacco cell nuclear extract and splicing of intron-containing tRNA(Met) precursors was then examined in wheat germ S23 extract and in the tobacco system. The results show that conversion of pre-tRNA(Met) to mature tRNA proceeds very efficiently in both plant extracts. In order to elucidate the potential role of specific nucleotides at the 3' and 5' splice sites and of a structured intron for pre-tRNA(Met) splicing in either extract, we have performed a systematic survey by mutational analyses. The results show that cytidine residues at intron-exon boundaries impair pre-tRNA(Met) splicing and that a highly structured intron is indispensable for pre-tRNA(Met) splicing. tRNA precursors with an extended anticodon stem of three to four base pairs are readily accepted as substrates by wheat and tobacco splicing endonuclease, whereas pre-tRNA molecules that can form an extended anticodon stem of only two putative base pairs are not spliced at all. An amber suppressor, generated from the intron-containing elongator tRNA(Met) gene, is efficiently processed and spliced in both plant extracts.

Molecular cloning and characterization of a nuclear gene encoding a putative subunit of tRNA splicing endonuclease from Arabidopsis thaliana

tRNA splicing endonuclease is required to produce mature tRNAs from intron-containing tRNA precursors. To characterize the structural features of plant endonuclease, we have isolated a cDNA and a corresponding genomic DNA clone from libraries of Arabidopsis thaliana which encode a putative subunit of the endonuclease. The gene product has an apparent mass of 27 kDa and contains a homologous domain of approximately 130 amino acids at the C-terminal region commonly found in other eucaryal and archaeal counterparts. Southern hybridization analysis of Arabidopsis genomic DNA utilizing the cDNA clone as probe indicates the presence of at least two related genes.

Expression of a zinc-binding domain of boar spermatidal transition protein 2 in Escherichia coli

Transition protein 2 (TP2; 137 amino acid residues) from boar late spermatid nuclei has three potential zinc finger motifs in the N-terminal 34 region. Gel shift assays revealed that boar TP2 recognized a CpG island sequence in a zinc-dependent manner. However, there was some nonspecific recognition of the oligonucleotide. Then, we constructed the expression system of zinc-binding domain of TP2 (TP2Z) (residues 1-103) in Escherichia coli. Double-stranded DNA fragments encoding TP2Z were synthesized as 18 fragments with 103 residues, annealed, and cloned into the expression plasmid pET11d. TP2Z was expressed upon induction with 1 mM isopropylthiogalactoside and extracted with acid including 0.71 M 2-mercaptoethanol. TP2Z was purified by ion-exchange chromatography on Fractogel EMD SO(-)(3) and HPLC on Nucleosil 300 7C18 and on Diol-120. Atomic absorption and CD spectroscopy showed that TP2Z bound three atoms of zinc per molecule of the protein and underwent a zinc-dependent conformational change in a manner similar to that for intact TP2. Gel shift assays indicated that TP2Z recognized a CpG island sequence more specifically than intact TP2 and that the specificity is dependent on zinc.

Transition protein 4 from boar late spermatid nuclei is a topological factor that stimulates DNA-relaxing activity of topoisomerase I

Transition protein 4 (TP4) from boar late spermatid nuclei, having higher affinity for double-stranded DNA and a local melting activity of DNA, stimulated SV40 DNA-relaxing activity of eukaryotic topoisomerase I at TP4/DNA molar ratios of 6.6-11. A TP4-spermidine mixture stimulated the activity of topoisomerase I much more than spermidine alone, but no more than TP4 alone, and poly-L-arginine did not. These results suggest that TP4 contributes to the chromatin reorganization in the late spermatid nuclei from nucleosomal-type structure with negatively supercoiled DNA to nucleoprotamine structure with no supercoiled DNA.

Molecular characterization of a gene for alanine aminotransferase from rice (Oryza sativa)

A cDNA clone encoding alanine aminotransferase (AlaAT) has isolated from randomly sequenced clones derived from a cDNA library of maturing rice seeds by comparison to previously identified genes. The deduced amino acid sequence was 88% and 91% homologous to those of the enzymes from barley and broomcorn millet (Panicum miliaceum), respectively. Using this cDNA as a probe, we isolated and sequenced the corresponding genomic clone. Comparison of the sequences of the cDNA and the genomic gene revealed that the coding region of the gene was interrupted by 14 introns 66 to 1547 bp long. Northern and western blotting analyses showed that the gene was expressed at high levels in developing seeds. When the 5'-flanking region between -930 and +85 from the site of initiation of transcription was fused to a reporter gene for beta-glucuronidase (GUS) and then introduced into the rice genome, histochemical staining revealed strong GUS activity in the inner endosperm tissue of developing seeds and weak activity in root tips. Similar tissue-specific expression was also detected by in situ hybridization. These results suggest that AlaAT is involved in nitrogen metabolism during the maturation of rice seed.

Plant cytosolic tRNAHis possesses an exceptional C54 in the canonical TPsiC loop

A nuclear gene coding for tRNAHis from Arabidopsis has been reported to contain C54in the TPsiC loop, although the corresponding nucleotide is an invariant U or a derivative in nearly all other tRNAs. The only previously reported plant cytosolic tRNAHis sequence, from lupin, has U54. To re-examine plant cytosolic tRNAsHis and their genes we have used DNA and RNA sequence analyses, restriction enzyme digestion of PCR-amplified tRNA genes, RNA hybridization and in vivo aminoacylation assays. Our results suggest that Arabidopsis nuclear tRNAHis genes ubiquitously contain C54, as do those from tobacco, lupin and pea. The C54 nucleotide is maintained in the mature tRNAHis, which is aminoacylated in vivo , but to a relatively low level compared with other tRNAs examined. Finally, it was shown that an Arabidopsis tRNAHis gene with T54in place of C54 is over 5-fold more transcriptionally active than the wild-type gene using an in vitro system derived from plant nuclei. A possible role for this apparently sub-optimal tRNAHis sequence is suggested.

Transition protein 1 from boar late spermatid nuclei having DNA-melting activity is a dimeric protein

Polyacrylamide gel electrophoretic behavior of boar transition protein 1, TP1, under dissociating and non-dissociating buffer conditions, and titration of fluorescently labeled TP1 with increasing amounts of TP1 showed that TP1 formed a dimer without intermolecular disulfide bond. TP1 dimer with intermolecular disulfide bond had similar DNA-melting activity to TP1, but was not detected in extracts from boar late spermatid nuclei. These results suggest that TP1 dimer without intermolecular disulfide bond induces local destabilization of DNA in the late spermatid nuclei.

Characterization of nuclear tRNA(Tyr) introns: their evolution from red algae to higher plants

We have previously isolated numerous intron-containing nuclear tRNA(Tyr) genes derived from either monocotyledonous (Triticum) or dicotyledonous (Arabidopsis, Nicotiana) plants by screening the corresponding genomic phage libraries with a synthetic tRNA(Tyr)-specific oligonucleotide. Here we have characterized additional tRNA(Tyr) genes from phylogenetically divergent plant species representing red algae (Champia), brown algae (Cystophyllum), green algae (Ulva), stonewort (Chara), liverwort (Marchantia), moss (Polytrichum), fern (Rumohra) and gymnosperms (Ginkgo) using amplification of the coding sequences from the corresponding genomic DNAs by polymerase chain reaction (PCR). All novel tRNA(Tyr) genes contain intervening sequences of variable sequence and length ranging in size from 11 to 21 bp. However, two features are conserved in all plant pre-tRNA(Tyr) introns: they possess a uridine and less frequently an adenosine at the 5' boundary and can adopt similar intron secondary structures in which an extended anticodon helix of 4-5 bp is formed by base-pairing between nucleotides of the intron and the anticodon loop. In order to elucidate the potential role of the highly conserved uridine at the first intron position, we have replaced it by all other nucleosides in an Arabidopsis pre-tRNA(Tyr) and have studied in wheat germ extract its effect on splicing and on conversion of U to psi in the GpsiA anticodon. Furthermore, we discuss the putative acquisition of tRNA(Tyr) introns at an early step of evolution after the separation of Archaea and Eucarya.

Isolation of intact transition protein 2 with three zinc finger motifs from boar late spermatid nuclei

Boar intact transition protein 2, TP2, was isolated from the late spermatid nuclei by chromatography on Fractogel EMD SO3- 650 (M), and HPLCs on Nucleosil 300 7C18, Diol-120 and Chemcosorb 3C18H. CD spectroscopy study showed that TP2 underwent a small but significant zinc dependent secondary structural change. TP2, having three potential zinc finger motifs, was shown to be contain 3 atoms of zinc bound per molecule of the protein by atomic absorption spectroscopy. These results together with the amino acid sequence of TP2 suggest that TP2 is a zinc metalloprotein with three zinc finger structures.

Plant nuclear tRNA(Met) genes are ubiquitously interrupted by introns

We have isolated three independent clones for nuclear elongator tRNA(Met) genes from an Arabidopsis DNA library using a tRNA(Met)-specific probe generated by PCR. Each of the coding sequences for tRNAMet in these clones is identical and is interrupted by an identical 11 bp long intervening sequence at the same position in the anticodon loop of the tRNA. Their sequences differ at two positions from the intron in a soybean counterpart. Southern analysis of Arabidopsis DNA demonstrates that a gene family coding for tRNA(Met) is dispersed at at least eight loci in the genome. The unspliced precursor tRNA(Met) intermediate was detected by RNA analysis using an oligonucleotide probe complementary to the putative intron sequence. In order to know whether introns commonly interrupt plant tRNA(Met) genes, their coding sequences were PCR-amplified from the DNAs of eight phylogenetically separate plant species. All 53 sequences determined contain 10 to 13 bp long intervening sequences, always positioned one base downstream from the anticodon. They can all be potentially folded into the secondary structure characteristic for plant intron-containing precursor tRNAs. Surprisingly, GC residues are always present at the 5'-distal end of each intron.

Striking differences in mitochondrial tRNA import between different plant species

A systematic comparison of the tRNAs imported into the mitochondria of larch, maize and potato reveals considerable differences among the three species. Larch mitochondria import at least eleven different tRNAs (more than half of those tested) corresponding to ten different amino acids. For five of these tRNAs [tRNA(Phe(GAA)), tRNA(Lys(CUU)), tRNA(Pro(UGG)), tRNA(Ser(GCU)) and tRNA(Ser(UGA))] this is the first report of import into mitochondria in any plant species. There are also differences in import between relatively closely related plants; wheat mitochondria, unlike maize mitochondria import tRNA(His), and sunflower mitochondria, unlike mitochondria from other angiosperms tested, import tRNA(Ser(GCU)) and tRNA(Ser(UGA)). These results suggest that the ability to import each tRNA has been acquired independently at different times during the evolution of higher plants, and that there are few apparent restrictions on which tRNAs can or cannot be imported. The implications for the mechanisms of mitochondrial tRNA import in plants are discussed.

Inhibition of endothelium-dependent relaxation by hemoglobin in rabbit aortic strips: comparison between acellular hemoglobin derivatives and cellular hemoglobins

Hemoglobin (Hb)-based artificial oxygen carriers are supposed to induce vasoconstriction through the inactivation of endothelium-derived relaxing factor (EDRF). We examined the vasoconstrictive activity of acellular Hb and cellular Hb solutions in rabbit aortic strips. Unmodified Hb, pyridoxalated Hb, bovine unmodified Hb, haptoglobin-Hb complex (Hp-Hb), and polyoxyethylene glycol-conjugated Hb (PEG-Hb) were used as acellular Hbs having different molecular masses. Cellular Hbs included liposome-encapsulated Hb and red blood cells (RBC). In the first experiment, Hb (10 ng/ml to 1 mg/ml) was cumulatively added to the tissues in which steady-state relaxation was evoked by acetylcholine (ACh) after precontraction induced by phenylephrine. Although all Hb solutions induced a dose-dependent reversal of ACh-induced relaxation, the most potent vasoconstrictive effect was noted with acellular Hbs, and their contractile activities were almost the same independent of molecular mass. On the other hand, liposome-Hb and RBC showed reduced potencies in this order. These results indicate the importance of cellularity as the major factor determining Hb-related EDRF inactivation. In another experiment, the tissues were exposed to Hb at 0.01, 0.1, or 1 mg/ml for 30 min and ACh-induced relaxation was recorded after the complete removal of Hb in an organ bath chamber. Exposure to unmodified Hb at > 0.1-mg/ml concentrations significantly reduced the ACh-induced relaxation, whereas the relaxation was not affected by PEG-Hb, Hp-Hb, liposome-Hb, or RBC. These results suggest that unmodified Hb might be persistently associated with tissues and thereby inhibit ACh-induced relaxation. From these findings, we propose two attributes of Hb-related inhibition of endothelium-dependent relaxation: Acellular Hbs inhibit EDRF more efficiently in the luminal space than cellular Hbs, and unmodified Hb can also inhibit it adluminally and/or adventitially.

Molecular cloning and sequencing of a nuclear gene encoding tRNA(Gln) (UUG) from Arabidopsis thaliana

A gene encoding cytoplasmic tRNA(Gln) (UUG) was isolated from an Arabidopsis DNA library. The coding sequence of the gene revealed 85% sequence identity with that of its animal counterparts. This is the first report of a nuclear tRNA(Gln) gene from higher plants.

Interaction of nucleosome core DNA with transition proteins 1 and 3 from boar late spermatid nuclei

The DNA binding properties of boar transition protein 1 and 3 (TP1 and TP3) were studied by means of physicochemical techniques. The ultraviolet difference absorption spectra upon TP1 and TP3 binding to rat liver nucleosome core DNA (double-stranded DNA) showed TP1- and TP3-induced hyperchromicity at 260 nm, which is suggestive of local melting of DNA. CD measurements of TP1-DNA and TP3-DNA complexes indicated that the binding of TP1 and TP3 induced different conformational changes in DNA, probably including local melting of DNA. Thermal melting studies on the binding of TP1 and TP3 to DNA showed that although at 1 mM NaCl TP1 and TP3 caused slight stabilization of the DNA against thermal melting, destabilization of the DNA was observed at 50 mM NaCl. From the results of quenching of the tyrosine fluorescence of TP1 and the tryptophan fluorescence of TP3 upon their binding to double-stranded and single-stranded boar liver nucleosome core DNA at 50 mM NaCl, the apparent association constants for the binding of TP1 to double- and single-stranded DNA were calculated to be 8.0 x 10(4) and 1.3 x 10(5) M-1, respectively, and those for the binding of TP3 to double- and single-stranded DNA to be 7.1 x 10(4) and 1.8 x 10(5) M-1, respectively. These results suggest that TP1 and TP3, having higher affinity for single-stranded DNA, induce local destabilization of DNA, probably through the stacking of Tyr32 and Trp18 with nucleic acid bases, respectively.

Touch-inducible genes for calmodulin and a calmodulin-related protein are located in tandem on a chromosome of Arabidopsis thaliana

Genes for calmodulin and calmodulin-related proteins in Arabidopsis are up-regulated by a variety of physical stimuli, which include rain, wind and touch [Braam and Davis (1990) Cell 60: 357]. We have isolated five genes for calmodulin (AtCAL1, 2, 3, 5, 6) and one gene for a calmodulin-related protein (AtCAL4) from an Arabidopsis genomic library. Touch stimulus of Arabidopsis plants induces the accumulation of mRNA transcribed from AtCAL4 and AtCAL5, but not from the other isolated genes. The two touch-inducible genes are arrayed in tandem with a short intergenic region of 700 bp but they show different organ-specific patterns of expression.

The amino acid sequence and interaction with the nucleosome core DNA of transition protein 4 from boar late spermatid nuclei

The primary structure of transition protein 4 (TP4) from boar late spermatid nuclei was determined by automated Edman degradation of S-pyridylethylated protein and of peptides generated by cleavage with Staphylococcus aureus V8 protease, lysyl endopeptidase and CNBr. Boar TP4 is a basic protein consisting of a highly basic amino-terminal half (residues 1-73) and a less basic carboxy-terminal half (residues 74-138). The latter half includes a highly hydrophobic segment, a four-times tandemly repeated sequence, N(G)QNKR(K)X, and a carboxy-terminal segment containing Trp126. Ultraviolet absorption and CD spectra of TP4-rat-liver-nucleosome-core-DNA (double-stranded DNA) complexes suggest a TP4-induced local melting of DNA. Although at 1 mM NaCl TP4 brought about a slight stabilization of the DNA against thermal melting, a destabilization of the DNA was observed at 50 mM NaCl. From the results of quenching of tryptophan (Trp126) fluorescence of TP4 upon its binding to double-stranded and single-stranded boar liver nucleosome-core DNA at 50 mM NaCl, the apparent association constants for the binding of TP4 to double-stranded and single-stranded DNA were calculated to be 7.3 x 10(3) M-1 and 4.1 x 10(3) M-1, respectively. These results suggest that TP4, having different domain structures from TP1-3 and a higher affinity for double-stranded DNA, induces a local destabilization of DNA probably through the stacking of Trp126 with nucleic acid bases.

Efficient Agrobacterium-mediated transformation of Arabidopsis thaliana using the bar gene as selectable marker

We have established an efficient Agrobacterium-mediated transformation procedure for Arabidopsis thaliana genotype C24 using the chimeric bialaphos resistance gene (bar) coding for phosphinothricin acetyltransferase (PAT). Hypocotyl explants from young seedlings cocultivated with agrobacteria carrying a bar gene were selected on shoot-inducing media containing different concentrations of phosphinothricin (PPT) which is an active component of bialaphos. We found that 20 mg/l of PPT completely inhibited the control explants from growing whereas the explants transformed with the bar gene gave rise to multiple shoots resistant to PPT after 3 weeks under the same selection conditions. The transformation system could also be applied to root explants. Resulting plantlets could produce viable seeds in vitro within 3 months after preparation of the explants. The stable inheritance of the resistance trait, the integration and expression of the bar gene in the progeny were confirmed by genetic tests, Southern analysis and PAT enzyme assay, respectively. In addition, the mature plants in soil showed tolerance to the herbicide Basta.

Isolation of intact transition protein 4 from boar late spermatid nuclei

Boar transition protein 4 was extracted with acid from the late spermatid nuclei, and separated from the transition protein-degrading proteases by ion-exchange chromatography on Fractogel EMD SO3- 650 (M). The transition protein was further purified by HPLCs on Nucleosil 300 7C18 and Diol-200. The circular dichroic spectra of the protein with and without dithiothreitol showed that the protein had beta-form predominantly. Although sodium dodecyl sulfate affected the tertially structure of the protein, the beta-form was well retained. These indicate that the protein has a structure-forming potential for the beta-structure.

Purification and characterization of a novel acrosin-like enzyme from boar cauda epididymal sperm

A trypsin-like protease was extracted with 1% cetyltrimethylammonium bromide (CTAB) at pH 7.0 from boar cauda epididymal sperm nuclei whose acrosin had previously been removed by acid extraction. The CTAB-extracted sperm protease (CSP) was purified by ion-exchange chromatography on CM-23, gel filtration on Sephadex G-100, affinity chromatography on benzamidine-CH-Sepharose 4B, and HPLC on CM-5PW. CSP is a two chain protein composed of M(r) 2.6K and M(r) 37K chains, which are covalently cross-linked by disulfide bonds. CSP exhibited a pH optimum between pH 8.0 and 9.0, and was inhibited by diisopropyl phosphorofluoridate, antipain, leupeptin, and 1-chloro-3-tosylamide-7-amino-L-2-heptanone. The activity of CSP was enhanced about 1.2-fold with 50 mM CaCl2, with which acrosin is enhanced 2.0-fold. The catalytic efficiency (kcat/Km) of CSP toward Bz-L-Arg-OEt, Tos-L-Arg-OMe, and Tos-L-Lys-OMe in the presence of 50 mM CaCl2 differed from that of acrosin by factors of 0.53, 1.2, and 0.80, respectively. Amino acid sequencing of V8-digested peptides of CSP, and its L- and H-chains showed that the amino acid sequence of CSP was closely related to, but different from, that of acrosin. These results suggest that CSP is a novel acrosin-like enzyme that differs from acrosin in its location in the sperm head, the effect of calcium ions on its activity, and its substrate specificity.

Isolation of intact transition protein 1 and 3 from boar late spermatid nuclei

Boar transition protein 1 and 3 were extracted with acid from the late spermatid nuclei, separated from the TP-degrading proteases by ion-exchange chromatography on Fractogel EMD SO3- 650 (M), and further purified by HPLCs on Diol-120 and on Hitachi #3057, respectively. The circular dichroic spectra of the transition proteins with and without dithiothreitol showed that they have beta-form predominantly. Although sodium dodecyl sulfate partially induced helical structure, the beta-form was considerably retained. These indicate that the transition proteins have a structure-forming potential for the beta-structure.

The amino acid sequence and phosphorylation sites of a boar transition protein 1

Boar transition protein 1 was extracted with acid from the testes, purified by chromatographies on CM-Sephadex C-25 and Sephadex G-50, and reduced and carboxymethylated. The modified protein was purified by HPLC on Nucleosil 300 7C18. The primary structure of the protein was determined by automated Edman degradation of the C-terminal peptide of the BrCN-cleaved protein and of the whole protein, and by carboxypeptidase digestion of it. The study of phosphorylation sites showed that Ser36 and Ser39 in the very conserved sequence 29-42 were partly phosphorylated, suggesting the involvement of this region in the interaction with DNA.

Oxygen transport and in vivo parameters of artificial red cells (ARC)

Artificial red cells (ARC) are prepared by encapsulating Hb with a polymerizable phospholipid. Their physical stability is very high and long-term preservation is possible in the frozen state. We examined the effect of blood parameters on the hematological and biochemical findings in transfused rats. The oxygen transport capacity of ARC in vivo were also tested by exchange transfusion in beagles. The oxygen binding parameters were almost the same as those of red blood cells (i.e., P50, Hill's coefficient, and oxygen transport efficiency (OTE) were 30 mmHg, 2.5, and 30%, respectively). The blood parameters after transfusion showed no significant changes when compared with the control. The oxygen transport capacity was of the same efficiency as red blood cells.

The amino acid sequence of a boar transition protein 3

The boar transition protein 3 (TP3) was extracted with acid from the isolated late spermatid nuclei or directly from the testes, fractionated with trichloroacetic acid, and reduced and carboxymethylated (RCM-). RCM-TP3 from the nuclei was purified by HPLCs on Nucleosil 300 7C18 and Hitachi #3057, and that from the testes, by ion-exchange chromatography on CM-Sephadex C-25 and HPLCs on Nucleosil 300 7C18 and Chemcosorb 7C8. The two TP3 preparations were identical in acid-urea- and SDS-gel electrophoretic mobilities and amino acid composition. The primary structure of TP3 was determined by manual Edman degradation of the peptides obtained by lysyl endopeptidase-digestion or by alpha-chymotrypsin-digestion of RCM-TP3 from the testes, and by automated Edman degradation of it. Boar TP3 is a basic protein of 76 residues: H-AKVTEKSWQPQTTSTKRWKKRKTPSQPRSRGKVRKIYKKVKRPLHVCSRKKYSPKVITTSRRQKRAR RANKFETIP-OH, and it shows 27% homology with boar TP1. TP3 is composed of an N-terminal region (1-19) having two characteristic tryptophan residues (8 and 18) which is absent in the known TP1 group, and a C-terminal region (20-76) having a close resemblance to boar TP1.

Acellular and cellular hemoglobin solutions as vasoconstrictive factor

The inhibitory effects of acellular and cellular hemoglobin (Hb) solutions on endothelium-dependent vasorelaxation were investigated in rabbit thoracic aortic strips. As acellular Hb solutions, 2,3-diphosphoglycerate (DPG)-depleted Hb and pyridoxylated Hb were examined. Cellular Hb solutions included washed human fresh red cells and liposome Hb encapsulated with pyridoxal-5'-phosphate (PLP). The tissues were precontracted with phenylephrine (PE), after which acetylcholine (ACh) was added to elicit a steady-state relaxation. Acellular Hb solutions cumulatively reversed ACh-induced relaxation, and these inhibitory effects reached a plateau at 10 micrograms/ml. Increasing oxygen affinity by pyridoxylation had little effect on this. In contrast, both red cells and liposome Hb solution showed moderate inhibitory effects, and they reached a plateau at 1 mg/ml. These findings indicate that acellular Hb solutions are more potent inhibitors than cellular Hb solutions by a factor of about 100, and that the encapsulation of Hb is a preferable method to mimic the red cell.

Efficient transformation of Arabidopsis thaliana: comparison of the efficiencies with various organs, plant ecotypes and Agrobacterium strains

The efficiency of Agrobacterium-mediated transformation of Arabidopsis thaliana was compared with different organs, Arabidopsis ecotypes, and Agrobacterium strains. Efficiency of shoot regeneration was examined using hypocotyl, cotyledon and root explants prepared from young seedlings. Hypocotyl expiants had the highest regeneration efficiency in all of the four Arabidopsis ecotypes tested, when based on a tissue culture system of callus-inducing medium (CIM: Valvekens et al. 1988) and shoot-inducing medium (SIM: Feldmann and Marks 1986). Histochemical analysis using the ß-glucuronidase (GUS) reporter gene showed that the gusA gene expression increased as the period of preincubation on CIM was extended, suggesting that dividing cells are susceptible to Agrobacterium infection. In order to obtain transgenic shoots, hypocotyl explants preincubated for 7 or 8 days on CIM were infected with Agrobacterium containing a binary vector which carries two drug-resistant genes as selection markers, and transferred to SIM for selection of transformed shoots. Of four Arabidopsis ecotypes and of three Agrobacterium strains examined, Wassilewskija ecotype and EHA101 strain showed the highest efficiency of regeneration of transformed shoots. By combining the most efficient factors of preincubation period, Arabidopsis ecotype, tissue, and bacterial strain, we obtained a transformation efficiency of about 80-90%. Southern analysis of 124 transgenic plants showed that 44% had one copy of inserted T-DNA while the others had more than one copy.

Stability and blood compatibility of polylipid/Hb

The Polylipid/Hb vesicle is a new artificial red cell (ARC) based on liposome-encapsulated Hb. Advantages are derived from the stabilized liposomal bilayer membranes, obtained by polymerization of 1,2-bis(2,4-octadecadienoyl)-sn-glycero-3-phospho choline (DODPC). Furthermore, blood compatibility in vitro are good.

Boar transition protein 2 and 4 isolated from late spermatid nuclei by high-performance liquid chromatography

The boar late spermatid nuclei retaining transition proteins (TPs) could be obtained from the testis by the use of antipain to inhibit TP-degrading proteinases of the nuclei. The enzymes detected in acid extract including the basic proteins were inactivated by reduction and carboxymethylation of the proteins. The reduced and carboxymethylated basic proteins were fractionated by differential precipitation between 3% trichloroacetic acid (TCA) and 3-20% TCA. From the 3% TCA-precipitate, boar TP2 and TP4 were isolated by high-performance liquid chromatography (HPLC) on Nucleosil 300 7C18. The two TPs were characterized by acid urea- and SDS-polyacrylamide gel electrophoreses and amino acid analysis. Boar TP2 closely resembled rat and mouse TP2s, and ram protein 3 in its high content of serine and basic amino acids, the presence of cysteine and molecular weight. Boar TP4 was similar to ram protein P1 in its high content of basic amino acids, the presence of cysteine and molecular weight. But the TP2 and TP4 differed in electrophoretic mobility on acid urea-gel and solubility in 3% TCA from those of the other species. The HPLC used here also enabled us to efficiently separate boar TP1, TP2, TP3 and TP4, and to estimate that the amount of the TP2, TP3 and TP4 was about 1/8, 1/4 and 1/4 that of the TP1, respectively.

Changes in chromatin structure of boar late spermatids to mature spermatozoa by using modification with dansyl chloride

Changes in the chromatin structure of boar late spermatids maturing to spermatozoa were studied by chemical modification of their nuclei with dansyl (Dns) chloride. Protamine was isolated from the dansylated boar spermatid and sperm nuclei, and its dansylated sites and degrees of dansylation were determined by sequence analysis. The N-terminal Ala-1, Tyr-3 and Tyr-42 of the protamine molecule in cauda epididymal sperm nuclei were dansylated 27%, 22% and 40%, respectively, whereas the respective residues in late spermatid nuclei were about 1.5-times as reactive as those in cauda epididymal sperm nuclei. However, the dansyl ratio of Tyr-3 to Tyr-42 remained unchanged from the late spermatid to mature sperm nuclei. SDS treatment did not affect the reactivity of cauda epididymal protamine and that of Ala-1 of caput epididymal protamine, but raised that of Tyr-3 and Tyr-42 of caput epididymal protamine by a factor of about 1.5. As a result of the SDS treatment, caput epididymal protamine came to have almost the same reactivity as late spermatid protamine. These facts suggest that the fundamental structure, in terms of DNA-protamine interaction, of sperm chromatin was already formed at the stage of the late spermatid, and then during epididymal transit the sperm chromatin was more tightly condensed, with increasing disulfide cross-links, thereby acquiring insensitivity towards the SDS-treatment.

The pyrogenicity of pertussis vaccine in mice and the factors in the vaccine responsible for this effect

The injection of whole cell pertussis vaccine into mice produced a biphasic fever reaction with two peaks appearing after about one and four hours, respectively. A method for the quantitative determination of each peak fever activity was developed and the factor responsible for each activity was investigated. The first and the second peak fever activities did not parallel each other in individual vaccines. The earlier fever activity appeared to correlate with endotoxin activity in individual vaccines while the later appeared to correlate with histamine-sensitizing factor (HSF) activity. The later peak fever activity was greatly reduced by heating the vaccine at 100 degrees C for 30 min while the first was little affected by such treatment. It was concluded that the fever activity of pertussis vaccine in mice may be ascribed to the combined actions of endotoxin and a heat-labile substance, possibly HSF.

Detection of antibodies to leptospiral genus-specific antigen in human and animal sera by indirect hemagglutination test with a partially purified genus-specific protein antigen

Antibodies against leptospiral genus-specific antigen were detected in the sera from clinically diagnosed human leptospirosis and suspected animal leptospirosis by indirect hemagglutination (IHA) test with a partially purified genus-specific protein antigen (GP-Ag). The reaction was positive in the infected humans and animals irrespective of the leptospiral serovars. No significant correlation was found between IHA titer against GP-Ag and microscopic agglutination (MA) titer. IHA titer did not always develop in parallel with MA titers. Sera obtained from healthy individuals were negative in both IHA and MA tests.

Swelling of the brain in mice caused by pertussis vaccine--its quantitative determination and the responsible factors in the vaccine

Intracerebral injection of vaccine into the mouse induced swelling of the brain. The swelling reached the maximum in the intensity by day 1 and persisted for several days. A method for quantitative determination of the brain-swelling activity of the vaccine was developed. A positive regression coefficient was found only between the brain-swelling and the lymphocytosis-promoting activities. Such activity was no longer shown with the vaccine heat-treated for 30 min at 80 C, but it was restored upon addition of the lymphocytosis-promoting factor (LPF) that caused no brain swelling by itself. The activity, therefore, was ascribed to cooperation of LPF and a certain heat-stable component other than endotoxin contained by pertussis vaccine.