Nematic structuring of transparent and multifunctional nanocellulose papers

The nematic structuring of cellulose nanofibers (CNFs) is proposed as a nanostructural engineering tool for exploiting the potential of CNFs in conceptually new "transparent papers". The nematic-structured CNF papers exhibit superior mechanical properties, optical transparency, gas-barrier properties, heat transfer properties and electrical resistivity, compared with conventional randomly-structured CNF papers.

C-Terminal Identification of AD74, a Proteolytic Product ofEnterococcus faecalisAggregation Substance: Application of Liquid Chromatography/Mass Spectrometry

Sexual aggregation involved in conjugative transfer of Enterococcus faecalis plasmid pAD1 is enhanced by the sex pheromone cAD1, which is excreted from recipient cells. A membrane-anchored 137 kDa protein is a pAD1-encoded aggregation substance designated asal, which is responsible for cell-cell contact and leads to the aggregation of cells. An AD74 protein is a proteolytic product corresponding to the N-terminal half of asal. The C-terminal of AD74 was identified as lysine at position 510 (K-510) by liquid chromatography/mass spectrometry (LC/MS): it indicates that asal is cleaved specifically between K-510 and G-511.

Structural Elucidation of Minor Components of Peptidyl Antibiotic P168s (Leucinostatins) by Tandem Mass Spectrometry

Tandem mass spectrometry with a four-sector type mass spectrometer was used to elucidate the structures of minor components of the peptidyl antibiotic P168s (leucinostatins). As N-terminal fragments, ions by B-type cleavage were dominant, while V-type cleavages were observed along with X, Y, and Z types as C-terminal ions. The V-type ions were predominant in the cleavages of the amino terminals of leucyl and hydroxyleucyl residues. The structures of several minor components could be deduced from the tandem mass spectra.

Peptidal Sex Hormones Inducing Conjugation Tube Formation in Compatible Mating-Type Cells of Tremella mesenterica

The pair of peptidal sex hormones (tremerogen A-10 and tremerogen a-13) that induce conjugation tube formation in compatible type cells (A and a types) of Tremella mesenterica were isolated. Tremerogen A-10 is a dodecapeptide and tremerogen a-13, a tridecapeptide. In both peptides, the sulfiydryl group of the cysteines at the carboxyl terminus was blocked by farnesyl moieties.

Amino acid sequence of a prothoracicotropic hormone of the silkworm Bombyx mori

We have determined the complete amino acid sequence of 4K-PTTH-II, one of three forms of the M(r) 4400 prothoracicotropic hormone of the silkworm Bombyx mori, active to brainless pupae of Samia cynthia ricini. Like vertebrate insulin, it consists of two nonidentical peptide chains (A and B chains). The A chain consists of 20 amino acid residues. The B chain is a mixture of four microheterogeneous peptides, two of which consist of 28 residues, and the other two, of 26 residues. 4K-PTTH-II has considerable sequence homology (40%) with human insulin, and it resembles porcine relaxin both in the carboxyl-terminal cysteine residue of the A chain and in the amino-terminal pyroglutamic acid residue of the B chain. The identical distribution of the six cysteine residues also indicates that 4K-PTTH-II belongs to the insulin family.

The S haplotypes lacking SLG in the genome of Brassica rapa

Self-incompatibility (SI) discriminating self- and non-self pollen is regulated by S-locus genes in Brassica. In most of the S haplotypes, a highly polymorphic S-locus glycoprotein ( SLG) gene is tightly linked to genes for the SI determinants, S-receptor kinase ( SRK) and SP11, although the precise function of SLG in SI has not been clarified. In the present study, we performed DNA gel blot analysis for S(32), S(33), and S(36) haplotypes of Brassica rapa showing normal SI phenotypes and concluded that there might be no SLG in their genome. RNA gel blot analysis of the SLG-less S haplotypes indicated the possible existence of eSRK transcripts in the stigma. These three S haplotypes are useful resources to discern the molecular mechanism of the SI reaction without SLG.

Daily use of dentifrice with and without xylitol and fluoride: effect on glucose retention in humans in vivo

The effect of daily use of three different dentifrices on glucose retention after glucose mouth rinsing was tested in this study regarding xylitol and fluoride. Six experimental groups used three different dentifrices produced by two different companies: xylitol- and fluoride-containing dentifrice (XF), non-xylitol- and fluoride-containing dentifrice (F), and non-xylitol- and non-fluoride-containing dentifrice (NonX-NonF). Subjects were divided at random and rinsed their mouths for 15s with 20ml of 0.5M glucose solution. Glucose and lactate retention were determined by collecting samples of saliva from the approximal areas of the maxillary and mandibular anterior teeth and using the enzyme membrane test. Samples were collected 0, 1 and 2 months after the start of regular dentifrice use. There were significant differences in glucose retention in relation to the dentifrice used, month of sampling, site of sampling, and time since start of rinsing. Their contribution ratios were 2.0, 4.4, 11.7 and 7.4%, respectively (P<0.01). There were significant differences observed between the XF and NonX-NonF groups, with the XF group presenting lower glucose retention than the NonX-NonF group. The XF group presented lower glucose retention than the F group. The F group showed lower glucose retention than the NonX-NonF group. There were significant differences in lactate retention in relation to the month and site of sampling, and their contribution ratios were 3.3 and 2.8%, respectively (P<0.01). There were, however, no significant differences in glucose and lactate retention in relation to the dentifrice manufacturer. It was concluded that the XF dentifrice was the most effective, and the F dentifrice was more effective in reducing glucose retention than the NonX-NonF dentifrice.

Characterization of expressed genes in the SLL2 region of self-compatible Arabidopsis thaliana

Self-incompatibility in Brassica species is regulated by a set of S-locus genes: SLG, SRK, and SP11/SCR. In the vicinity of the S-locus genes, several expressed genes, SLL2 and SP2/ClpP, etc., were identified in B. campestris. Arabidopsis thaliana is a self-compatible Brassica relative, and its complete genome has been sequenced. From comparison of the genomic sequences between B. campestris and A. thaliana, microsynteny between gene clusters of Arabidopsis and Brassica SLL2 regions was observed, though the S-locus genes, SLG, SRK, and SP11/SCR were not found in the region of Arabidopsis. Almost all genes predicted in this region of Arabidopsis were expressed in both vegetative and reproductive organs, suggesting that the genes in the SLL2 region might not be related to self-incompatibility. Considering the recent speculation that the S-locus genes were translocated as a single unit between Arabidopsis and Brassica, the translocation might have occurred in the region between the SLL2 and SP7 genes.

Direct ligand-receptor complex interaction controls Brassica self-incompatibility

Many higher plants have evolved self-incompatibility mechanisms to prevent self-fertilization. In Brassica self-incompatibility, recognition between pollen and the stigma is controlled by the S locus, which contains three highly polymorphic genes: S-receptor kinase (SRK), S-locus protein 11 (SP11) (also called S-locus cysteine-rich protein; SCR) and S-locus glycoprotein (SLG). SRK encodes a membrane-spanning serine/threonine kinase that determines the S-haplotype specificity of the stigma, and SP11 encodes a small cysteine-rich protein that determines the S-haplotype specificity of pollen. SP11 is localized in the pollen coat. It is thought that, during self-pollination, SP11 is secreted from the pollen coat and interacts with its cognate SRK in the papilla cell of the stigma to elicit the self-incompatibility response. SLG is a secreted stigma protein that is highly homologous to the SRK extracellular domain. Although it is not required for S-haplotype specificity of the stigma, SLG enhances the self-incompatibility response; however, how this is accomplished remains controversial. Here we show that a single form of SP11 of the S8 haplotype (S8-SP11) stabilized with four intramolecular disulphide bonds specifically binds the stigma membrane of the S8 haplotype to induce autophosphorylation of SRK8, and that SRK8 and SLG8 together form a high-affinity receptor complex for S8-SP11 on the stigma membrane.

Dual targeting of spinach protoporphyrinogen oxidase II to mitochondria and chloroplasts by alternative use of two in-frame initiation codons

Protoporphyrinogen oxidase (Protox) is the final enzyme in the common pathway of chlorophyll and heme biosynthesis. Two Protox isoenzymes have been described in tobacco, a plastidic and a mitochondrial form. We isolated and sequenced spinach Protox cDNA, which encodes a homolog of tobacco mitochondrial Protox (Protox II). Alignment of the deduced amino acid sequence between Protox II and other tobacco mitochondrial Protox homologs revealed a 26-amino acid N-terminal extension unique to the spinach enzyme. Immunoblot analysis of spinach leaf extract detected two proteins with apparent molecular masses of 57 and 55 kDa in chloroplasts and mitochondria, respectively. In vitro translation experiments indicated that two translation products (59 and 55 kDa) are produced from Protox II mRNA, using two in-frame initiation codons. Transport experiments using green fluorescent protein-fused Protox II suggested that the larger and smaller translation products (Protox IIL and IIS) target exclusively to chloroplasts and mitochondria, respectively.

Sequence comparisons among dispersed members of the Brassica S multigene family in an S9 genome

Self-incompatibility (SI) systems prevent self-pollination and promote outbreeding. In Brassica, the SI genes SLG (for S-locus glycoprotein) and SRK (for S-receptor kinase) are members of the S multigene family, which share the SLG-like domain (S domain), which encodes a putative receptor. We have cloned members of the S multigene family from the S9 haplotype of B. campestris (syn. rapa). In addition, eight distinct genomic regions harboring 10 SLG/SRK-like genes were characterized in the present study. Sequence analysis revealed two novel SRK-like genes, BcRK3 and BcRK6 (for B. campestris receptor kinases 3 and 6, respectively). Other genes that were characterized included SFR2 (for S gene family receptor 2), SLR2 (for S locus related gene 2), and a pseudogene. Based on phylogenetic analysis of the nucleotide sequences of the S domain regions, SLG and SRK appear to be distinct from other members of the S multigene family. Linkage analysis showed that most members of the S multigene family are dispersed in the Brassica genome, and that SLR1 (S locus related gene 1) is not linked to the SLR2 in B. campestris.

The S receptor kinase gene determines dominance relationships in stigma expression of self-incompatibility in Brassica

Self-incompatibility (SI) in Brassica is sporophytically controlled by the multi-allelic S locus. SI phenotypes of the stigma and pollen in an S heterozygote are determined by the two S haplotypes it carries; the two haplotypes may be co-dominant or exhibit a dominant/recessive relationship. Because the S receptor kinase (SRK) gene of the S locus was recently shown to determine the S haplotype specificity of the stigma, we wished to investigate whether SRK also plays a role in the dominance relationships between S haplotypes. We crossed plants carrying an SRK28 transgene with plants homozygous for one of five S haplotypes that are either co-dominant with, or recessive to, S28 haplotype in the stigma, and analyzed the SI phenotypes of the progeny. In all cases, the SI phenotype of the stigma of plants carrying the SRK28 transgene could be predicted by the known dominance relationships between the S haplotype(s) and the S28 haplotype. Moreover, in the S43 homozygote carrying the SRK28 transgene where the S43 phenotype in the stigma was masked by the presence of the SRK28, the transcript level of SRK28 was found to be much lower than that of SRK43. All these results suggest that the dominance relationships between S haplotypes in the stigma are determined by SRK, but not by virtue of its relative expression level.

A pollen coat protein, SP11/SCR, determines the pollen S-specificity in the self-incompatibility of Brassica species

Many flowering plants have evolved self-incompatibility (SI) systems to prevent inbreeding. In the Brassicaceae, SI is genetically controlled by a single polymorphic locus, termed the S-locus. Pollen rejection occurs when stigma and pollen share the same S-haplotype. Recognition of S-haplotype specificity has recently been shown to involve at least two S-locus genes, S-receptor kinase (SRK) and S-locus protein 11 or S-locus Cys-rich (SP11/SCR). SRK encodes a polymorphic membrane-spanning protein kinase, which is the sole female determinant of the S-haplotype specificity. SP11/SCR encodes a highly polymorphic Cys-rich small basic protein specifically expressed in the anther tapetum and in pollen. In cauliflower (B. oleracea), the gain-of-function approach has demonstrated that an allele of SP11/SCR encodes the male determinant of S-specificity. Here we examined the function of two alleles of SP11/SCR of B. rapa by the same approach and further established that SP11/SCR is the sole male determinant of SI in the genus Brassica sp. Our results also suggested that the 522-bp 5'-upstream region of the S9-SP11 gene used to drive the transgene contained all the regulatory elements required for the unique sporophytic/gametophytic expression observed for the native SP11 gene. Promoter deletion analyses suggested that the highly conserved 192-bp upstream region was sufficient for driving this unique expression. Furthermore, immunohistochemical analyses revealed that the protein product of the SP11 transgene was present in the tapetum and pollen, and that in pollen of late developmental stages, the SP11 protein was mainly localized in the pollen coat, a finding consistent with its expected biological role.

Use of fluoridated dentifrice and glucose retention at the approximal areas of anterior teeth

The present study was undertaken to learn to what extent the use of dentifrice with fluoride affected glucose retention after glucose rinsing. Fifty-eight subjects consisting of forty male adults and eighteen female adults whose average age was 21.9 years were divided at random into two groups; one group used fluoridated dentifrice and the other group used nonfluoridated dentifrice. Subjects rinsed their mouths for fifteen seconds with 20 mL of 0.5 M glucose solution. Samples of saliva were taken from the approximal areas between the right and left central incisors of the maxilla and mandible by inserting the tip portion of a paper point three-minutes after the glucose rinsing, sample of saliva were taken from the neighboring approximal areas of the left central and left lateral incisors. Glucose content of the paper points was determined using the enzyme membrane method. Determinations were made before and at the end of the first, third, and fifth month over a five-month period. Fluoride concentrations in the resting saliva were also determined in different months during this period. At three-minutes and six-minutes, glucose retention in the group using fluoridated dentifrice was found to decrease slightly throughout the experiment; while glucose retention in the group on nonfluoridated dentifrice leveled off or increased in the fifth month. Fluoride concentration in the resting saliva increased during the experiment in the group using fluoridated dentifrice; while fluoride concentration in the group using nonfluoridated dentifrice did not change. It was concluded that the regular use of fluoridated dentifrice made glucose retention slightly lower and fluoride level in whole saliva higher.

Blasticidin A as an inhibitor of aflatoxin production by Aspergillus parasiticus

Blasticidin A, an antibiotic, showed strong inhibitory activity toward aflatoxin production by Aspergillus parasiticus. Its structure was characterized by NMR and chemical degradation experiments as 1, which is a tetramic acid derivative with a highly oxygenated long alkyl chain similar to aflastatin A (2). Absolute configurations of the eight chiral centers at C-4, 6, 31, 32, 33, 34, 35 and 37 of 1 were chemically determined. Blasticidin A almost completely inhibited aflatoxin production at 0.5 microM.

Flagellin from an incompatible strain of Pseudomonas avenae induces a resistance response in cultured rice cells

The host range of Pseudomonas avenae is wide among monocotyledonous plants, but individual strains can infect only one or a few host species. The resistance response of rice cells to pathogens has been previously shown to be induced by a rice-incompatible strain, N1141, but not by a rice-compatible strain, H8301. To clarify the molecular mechanism of the host specificity in P. avenae, a strain-specific antibody that was raised against N1141 cells and then absorbed with H8301 cells was prepared. When a cell extract of strain N1141 was separated by SDS-polyacrylamide gel electrophoresis and immunostained with the N1141 strain-specific antibody, only a flagellin protein was detected. Purified N1141 flagellin induced the hypersensitive cell death in cultured rice cells within 6 h of treatment, whereas the H8301 flagellin did not. The hypersensitive cell death could be blocked by pretreatment with anti-N1141 flagellin antibody. Furthermore, a flagellin-deficient N1141 strain lost not only the induction ability of hypersensitive cell death but also the expression ability of the EL2 gene, which is thought to be one of the defense-related genes. These results demonstrated that the resistance response in cultured rice cells is induced by the flagellin existing in the incompatible strain of P. avenae but not in the flagellin of the compatible strain.

[Continuous hepatic arterial infusion of 5-fluorouracil with leucovorin for unresectable liver metastases from colorectal cancer]

Twenty-three patients with liver metastases from colorectal cancer were treated by continuous hepatic arterial infusion chemotherapy with 5-FU and Leucovorin. The regimen was that 500 mg/body of 5-FU with 30 mg/body of Leucovorin was administered continuously for 5 days, followed by no medication for 16 days. The effect of this therapy was evaluated and the relationship between this therapy and the overexpression of vascular endothelial growth factor (VEGF) or microvessel density (MVD) was also studied. Complete response was obtained in 4 patients and partial response in 3 patients; the response rate was 32%. The response rate was 60% in patients who underwent more than 7 courses. The response rate was 44% in patients with positive VEGF and 33% in patients with negative VEGF. The response rate was 50% in patients with an MVD of more than 30 and 33% in patients with an MVD of less than 30. The 3-year survival rate for patients who underwent more than 7 courses was 37.5%. This therapy had to be abandoned in 6 patients due to occlusion of the catheter. Skillful maintenance of the catheter is necessary for a high response rate and satisfactory prognosis using this therapy.

Molecular characterization and subcellular localization of protoporphyrinogen oxidase in spinach chloroplasts

Protoporphyrinogen oxidase (Protox) is the last common enzyme in the biosynthesis of chlorophylls and heme. In plants, there are two isoenzymes of Protox, one located in plastids and other in the mitochondria. We cloned the cDNA of spinach (Spinacia oleracea) plastidal Protox and purified plastidal Protox protein from spinach chloroplasts. Sequence analysis of the cDNA indicated that the plastid Protox of spinach is composed of 562 amino acids containing the glycine-rich motif GxGxxG previously proposed to be a dinucleotide binding site of many flavin-containing proteins. The cDNA of plastidal Protox complemented a Protox mutation in Escherichia coli. N-terminal sequence analysis of the purified enzyme revealed that the plastidal Protox precursor is processed at the N-terminal site of serine-49. The predicted transit peptide (methionine-1 to cysteine-48) was sufficient for the transport of precursors into the plastid because green fluorescent protein fused with the predicted transit peptide was transported to the chloroplast. Immunocytochemical analysis using electron microscopy showed that plastidal Protox is preferentially associated with the stromal side of the thylakoid membrane, and a small portion of the enzyme is located on the stromal side of the chloroplast inner envelope membrane.

Purification and properties of protoporphyrinogen oxidase from spinach chloroplasts

Protoporphyrinogen oxidase (Protox), an enzyme that catalyzes the common step of chlorophyll and heme biosynthetic pathways, was purified from spinach chloroplasts. The molecular weight of purified protein was estimated to be approximately 60,000 by SDS-PAGE. Protox activity was stimulated by addition of FAD, suggesting that chloroplast Protox requires FAD as a cofactor. Furthermore, the Protox-inhibiting herbicide, S23142, specifically inhibited the purified Protox activity at an IC50 value of 1 nM.

Reduced levels of chloroplast FtsH protein in tobacco mosaic virus-infected tobacco leaves accelerate the hypersensitive reaction

In tobacco cultivars resistant to tobacco mosaic virus (TMV), infection results in the death of the infected cells accompanying the formation of necrotic lesions. To identify the genes involved in this hypersensitive reaction, we isolated the cDNA of tobacco DS9, the transcript of which decreases before the appearance of necrotic lesions. The DS9 gene encodes a chloroplastic homolog of bacterial FtsH protein, which serves to maintain quality control of some cytoplasmic and membrane proteins. A large quantity of DS9 protein was found in healthy leaves, whereas the quantity of DS9 protein in infected leaves decreased before the lesions appeared. In transgenic tobacco plants containing less and more DS9 protein than wild-type plants, the necrotic lesions induced by TMV were smaller and larger, respectively, than those on wild-type plants. These results suggest that a decrease in the level of DS9 protein in TMV-infected cells, resulting in a subsequent loss of function of the chloroplasts, accelerates the hypersensitive reaction.

Highly divergent sequences of the pollen self-incompatibility (S) gene in class-I S haplotypes of Brassica campestris (syn. rapa) L

Self-incompatibility (SI) enables flowering plants to discriminate between self- and non-self-pollen. In Brassica, SI is controlled by the highly polymorphic S locus. The recently identified male determinant, termed SP11 or SCR, is thought to be the ligand of S receptor kinase, the female determinant. To examine functional and evolutionary properties of SP11, we cloned 14 alleles from class-I S haplotypes of Brassica campestris and carried out sequence analyses. The sequences of mature SP11 proteins are highly divergent, except for the presence of conserved cysteines. The phylogenetic trees suggest possible co-evolution of the genes encoding the male and female determinants.

Alteration of the self-incompatibility phenotype in Brassica by transformation of the antisense SLG gene

Self-incompatible (SI) Brassica rapa (syn. B. campestris) was transformed with an antisense SLG gene by using SLG8 cDNA isolated from the B. campestris S8 homozygote. Two transformed lines were obtained and analyzed. Northern blot and Western blot analyses revealed that endogenous SLG and SRK were greatly reduced of the transcriptional and translational levels in the transformant. Pollination experiments confirmed that their SI phenotype had broken down. In addition, the progeny with the antisense SLG gene, resulting from self- or cross-pollination of the transgenic plant, also showed the self-compatible phenotype. The breakdown of SI in the tranformants was due to the change in property of the stigma and not of the pollen. These results provide strong evidence that SLG and/or SRK is implicated in the pollen-stigma recognition of SI and that they act only as stigmatic factors.

Isolation and characterization of pollen coat proteins of Brassica campestris that interact with S locus-related glycoprotein 1 involved in pollen-stigma adhesion

Adhesion of pollen grains to the stigmatic surface is a critical step during sexual reproduction in plants. In Brassica, S locus-related glycoprotein 1 (SLR1), a stigma-specific protein belonging to the S gene family of proteins, has been shown to be involved in this step. However, the identity of the interacting counterpart in pollen and the molecular mechanism of this interaction have not been determined. Using an optical biosensor immobilized with S gene family proteins, we detected strong SLR1-binding activity in pollen coat extracts of Brassica campestris. Two SLR1-binding proteins, named SLR1-BP1 and SLR1-BP2, were identified and purified by the combination of SLR1 affinity column chromatography and reverse-phase HPLC. Sequence analyses revealed that these two proteins (i) differ only in that a proline residue near the N terminus is hydroxylated in SLR1-BP1 but not in SLR1-BP2, and (ii) are members of the class A pollen coat protein (PCP) family, which includes PCP-A1, an SLG (S locus glycoprotein)-binding protein isolated from Brassica oleracea. Kinetic analysis showed that SLR1-BP1 and SLR1-BP2 specifically bound SLR1 with high affinity (K(d) = 5.6 and 4.4 nM, respectively). The SLR1-BP gene was specifically expressed in pollen at late stages of development, and its sequence is highly conserved in Brassica species with the A genome.

The S receptor kinase determines self-incompatibility in Brassica stigma

The self-incompatibility possessed by Brassica is an intraspecific reproductive barrier by which the stigma rejects self-pollen but accepts non-self-pollen for fertilization. The molecular/biochemical bases of recognition and rejection have been intensively studied. Self-incompatibility in Brassica is sporophytically controlled by the polymorphic S locus. Two tightly linked polymorphic genes at the S locus, S receptor kinase gene (SRK) and S locus glycoprotein gene (SLG), are specifically expressed in the papillar cells of the stigma, and analyses of self-compatible lines of Brassica have suggested that together they control stigma function in self-incompatibility interactions. Here we show, by transforming self-incompatible plants of Brassica rapa with an SRK28 and an SLG28 transgene separately, that expression of SRK28 alone, but not SLG28 alone, conferred the ability to reject self (S28)-pollen on the transgenic plants. We also show that the ability of SRK28 to reject S28 pollen was enhanced by SLG28. We conclude that SRK alone determines S haplotype specificity of the stigma, and that SLG acts to promote a full manifestation of the self-incompatibility response.

The pollen determinant of self-incompatibility in Brassica campestris

Many flowering plants possess self-incompatibility (SI) systems that prevent inbreeding. In Brassica, SI is controlled by a single polymorphic locus, the S locus. Two highly polymorphic S locus genes, SLG (S locus glycoprotein) and SRK (S receptor kinase), have been identified, both of which are expressed predominantly in the stigmatic papillar cell. We have shown recently that SRK is the determinant of the S haplotype specificity of the stigma. SRK is thought to serve as a receptor for a pollen ligand, which presumably is encoded by another polymorphic gene at the S locus. We previously have identified an S locus gene, SP11 (S locus protein 11), of the S(9) haplotype of Brassica campestris and proposed that it potentially encodes the pollen ligand. SP11 is a novel member of the PCP (pollen coat protein) family of proteins, some members of which have been shown to interact with SLG. In this work, we identified the SP11 gene from three additional S haplotypes and further characterized the gene. We found that (i) SP11 showed an S haplotype-specific sequence polymorphism; (ii) SP11 was located in the immediate flanking region of the SRK gene of the four S haplotypes examined; (iii) SP11 was expressed in the tapetum of the anther, a site consistent with sporophytic control of Brassica SI; and (iv) recombinant SP11 of the S(9) haplotype applied to papillar cells of S(9) stigmas, but not of S(8) stigmas, elicited SI response, resulting in inhibition of hydration of cross-pollen. All these results taken together strongly suggest that SP11 is the pollen S determinant in SI.

Absolute configuration of aflastatin A, a specific inhibitor of aflatoxin production by Aspergillus parasiticus

Aflastatin A (1) is a specific inhibitor of aflatoxin production by Aspergillus parasiticus. It has the novel structure of a tetramic acid derivative with a long alkyl side chain. The absolute configurations of 29 chiral centers contained in 1 were chemically elucidated in this study. First, four small fragment molecules were prepared from 1 or its methyl ether (2), and their absolute structures were assigned as N-methyl-D-alanine, (2S,4R)-2, 4-dimethyl-1,6-hexanediol dibenzoate, (R)-3-hydroxydodecanoic acid, and (R)-1,2,4-butanetriol tribenzoate. Next, an acyclic fragment molecule 3 with 13 chiral centers was obtained from 1 by NaIO(4) oxidation, and its relative stereochemistry was elucidated by J-based configuration analysis. By analyzing coupling constants of (3)J(H,H) and (2,3)J(C,H) and ROE data, the relative configuration of 3 was verified. Finally, by further J-based configuration analysis using a fragment molecule 7 prepared from 2 with 28 chiral carbons, all relative configurations in the alkyl side chain of 1 were clarified. By connecting these relative configurations with the absolute configurations of first four fragment molecules, the absolute stereochemistry of 1 was fully determined.

Prothoracicotropic activity of SBRPs, the insulin-like peptides of the saturniid silkworm Samia cynthia ricini

Synthesis and secretion of the insect molting hormone ecdysteroid in the prothoracic glands (PGs) are stimulated by the prothoracicotropic hormone (PTTH) secreted by the brain. Bombyxins, insulin-like peptides of the silkworm Bombyx mori, show prothoracicotropic activity when administered to the saturniid silkworm Samia cynthia ricini, but they are inactive to B. mori itself. Recently, the genes for the bombyxin homologs of S. cynthia ricini (referred to as Samia bombyxin-related peptides, SBRPs) were cloned. To examine the prothoracicotropic activity of SBRPs on S. cynthia ricini, we synthesized two representative molecules, SBRP-A1 and -B1. They promoted pupa-to-adult development with ED(50) of 50 and 10 ng/pupa (EC(50) of 5 and 1 nM), respectively.

Relationship between polyploidy and pollen self-incompatibility phenotype in Petunia hybrida Vilm

Self-incompatibility in Solanaceae is controlled by a single multiallelic locus, the S-locus. The S-allele associated ribonucleases (S-RNases) in the pistil are involved in pollen rejection. In this work, we analyzed two newly isolated lines of Petunia hybrida, termed PB and PF. They both had the same set of S-RNases (SB1- and SB2-RNases), however the PB was a self-incompatible diploid while PF was a self-compatible tetraploid. Cross pollination tests between PB and PF indicated diploid pollen from PF lost the incompatibility phenotype. In order to clarify the effects of polyploidy on pollen phenotypic change, we artificially induced tetraploid plants from a diploid SB1SB2 heterozygote (= PB) and a diploid SB1SB1 homozygote. The obtained SB1 SB1SB1SB1 homoallelic tetraploid remained self-incompatible, whereas the SB1SB1SB2SB2 heteroallelic tetraploid became self-compatible. These data suggested that the diploid heteroallelic pollen lost the incompatibility phenotype and had the characteristics of self-compatibility with SB1SB2 style.

Genomic organization of the S locus: Identification and characterization of genes in SLG/SRK region of S(9) haplotype of Brassica campestris (syn. rapa)

In Brassica, two self-incompatibility genes, encoding SLG (S locus glycoprotein) and SRK (S-receptor kinase), are located at the S locus and expressed in the stigma. Recent molecular analysis has revealed that the S locus is highly polymorphic and contains several genes, i.e., SLG, SRK, the as-yet-unidentified pollen S gene(s), and other linked genes. In the present study, we searched for expressed sequences in a 76-kb SLG/SRK region of the S(9) haplotype of Brassica campestris (syn. rapa) and identified 10 genes in addition to the four previously identified (SLG(9), SRK(9), SAE1, and SLL2) in this haplotype. This gene density (1 gene/5.4 kb) suggests that the S locus is embedded in a gene-rich region of the genome. The average G + C content in this region is 32.6%. An En/Spm-type transposon-like element was found downstream of SLG(9). Among the genes we identified that had not previously been found to be linked to the S locus were genes encoding a small cysteine-rich protein, a J-domain protein, and an antisilencing protein (ASF1) homologue. The small cysteine-rich protein was similar to a pollen coat protein, named PCP-A1, which had previously been shown to bind SLG.

Centromeric localization of an S-RNase gene in Petunia hybrida Vilm

S-RNase has been identified to be an S-allele-specific stylar determinant contributing to the self-incompatibility response in Solanaceae. In order to examine the physical location of the S-RNase gene, multi-color fluorescence in situ hybridization (FISH) using the S (B1) -RNase cDNA probe and ribosomal RNA gene (rDNA) probe was performed on an S (B1) S (B2 )heterozygote of Petunia hybrida. The S (B1) -RNase gene was detected as a doublet signal close to the centromere of chromosome III. Next, we performed FISH using a large genome probe prepared from a λSB1-311 clone (20 kb) which contains the S (B1) -RNase gene and its 3´ flanking region. This probe hybridized to the centromeric regions of all P. hybrida chromosomes. Sequence analysis of the λSB1-311 clone revealed the presence of a repetitive sequence consisting of a novel 666 bp unit sequence. A subclone (pBS-SB1B5) containing this unit sequence also hybridized to all of the centromeric regions, confirming that this unit is the centromeric specific repetitive sequence. These data suggested that the S ( B1 ) -RNase gene is located very close to (within a distance of 12 kb from) the centromeric-specific repetitive sequence. Likewise, the pBS-SB1B5 probe hybridized to the centromeric regions of all chromosomes in P. littoralis, another Petunia species. However, the probe did not hybridize to the centromere of the chromosomes from other species in Solanaceae. These results suggested that this centromeric repetitive sequence might be a genus-specific one.

Introduction of SLG (S locus glycoprotein) alters the phenotype of endogenous S haplotype, but confers no new S haplotype specificity in Brassica rapa L

Self-incompatibility (SI) in Brassicaceae is genetically controlled by the S locus complex in which S locus glycoprotein (SLG) and S receptor kinase (SRK) genes have been identified, and these two genes encoding stigma proteins are believed to play important roles in SI recognition reaction. Here we introduced the SLG43 gene of Brassica rapa into a self-incompatible cultivar, Osome, of B. rapa, and examined the effect of this transgene on the SI behavior of the transgenic plants. Preliminary pollination experiments demonstrated that Osome carried S52 and S60, and both were codominant in stigma, but S52 was dominant to S60 in pollen. S43 was found to be recessive to S52 and codominant with S60 in stigma. The nucleotide sequence of SLG43 was more similar to that of SLG52 (87.8% identity) than to that of SLG60 (74.8% identity). Three of the ten primary transformants (designated No. 1 to No. 10) were either completely (No. 9) or partially (No. 6 and No. 7) self-compatible; the SI phenotype of the stigma was changed from S52S60 to S60, but the SI phenotype of the pollen was not altered. In these three plants, the mRNA and protein levels of both SLG43 and SLG52 were reduced, whereas those of SLG60 were not. All the plants in the selfed progeny of No. 9 and No. 6 regained SI and they produced a normal level of SLG52. These results suggest that the alteration of the SI phenotype of the stigma in the transformants Nos. 6, 7, and 9 was the result of specific co-suppression between the SLG43 transgene and the endogenous SLG52 gene. Three of the transformants (Nos. 5, 8 and 10) produced SLG43 protein, but their SI phenotype was not altered. The S60 homozygotes in the selfed progeny of No. 10 which produced the highest level of SLG43 were studied because S43 was codominant with S60 in the stigma. They produced SLG43 at approximately the same level as did S43S60 heterozygotes, but did not show S43 haplotype specificity at the stigma side. We conclude that SLG is necessary for the expression of the S haplotype specificity in the stigma but the introduction of SLG alone is not sufficient for conferring a novel S haplotype specificity to the stigma.

Structures and biosynthesis of aflastatins: novel inhibitors of aflatoxin production by Aspergillus parasiticus

Two novel inhibitors of aflatoxin production by Aspergillus parasiticus were isolated from the mycelial extracts of Streptomyces sp. MRI142 and termed aflastatin A and B. The structures of aflastatin A (1) and B (5) were elucidated by NMR and chemical degradation experiments. These compounds have a novel skeleton of a tetramic acid derivative with a highly oxygenated long alkyl chain. The incorporation experiments using 13C-labeled acetates, propionate, glucose and glycolate suggested that most of the C2 and C3 units involved in the alkyl chain moiety of aflastatin A were biosynthesized from acetic and propionic acids, but five C2 units in the alkyl chain originated from glycolic acid.

Direct cloning of the Brassica S locus by using a P1-derived artificial chromosome (PAC) vector

Self-incompatibility of Brassica is regulated by the S locus, which contains several genes including SLG and SRK. We found that both SLG and SRK genes were located at an approx. 80-kb MluI fragment in an S9 haplotype of B. campestris. Therefore, we cloned this MluI fragment into a BssHII site of the P1-derived artificial chromosome (PAC) vector. The utility of the direct cloning method is discussed in this study.

Three members of the S multigene family are linked to the S locus of Brassica

Two self-incompatibility genes in Brassica, SLG and SRK (SLG encodes a glycoprotein; SRK encodes a receptor-like kinase), are included in the S multigene family. Products of members of the S multigene family have an SLG-like domain (S domain) in common, which may function as a receptor. In this study, three clustered members of the S multigene family, BcRK1, BcRL1 and BcSL1, were characterized. BcRK1 is a putative functional receptor kinase gene expressed in leaves, flower buds and stigmas, while BcRL1 and BcSL1 are considered to be pseudogenes because deletions causing frameshifts were identified in these sequences. Sequence and expression pattern of BcRK1 were most similar to those of the Arabidopsis receptor-like kinase gene ARK1, indicating that BcRK1 might have a function similar to that of ARK1, in processes such as cell expansion or plant growth. Interestingly, the region containing BcRK1, BcRL1 and BcSL1 is genetically linked to the S locus and the physical distance between SLG, SRK and the three S-related genes was estimated to be less than 610 kb. Thus the genes associated with self-incompatibility exist within a cluster of S-like genes in the genome of Brassica.

Molecular cloning of a new type of cDNA for pheromone biosynthesis activating neuropeptide in the silkworm, Bombyx mori

A neuropeptide named pheromone biosynthesis activating neuropeptide (PBAN) stimulates the pheromone production of lepidopteran insects. We have identified a different type of cDNA for PBAN, which shows two amino acid replacements in the region of the PBAN sequence previously reported. Single strand conformation polymorphism (SSCP) analysis revealed that the two types of cDNA originated from two allelic variants of the gene for PBAN.

Globular and fibrous structure in barley chromosomes revealed by high-resolution scanning electron microscopy

Barley chromosomes were prepared for high-resolution scanning electron microscopy using a combination of enzyme maceration, treatment in acetic acid and osmium impregnation using thiocarbohydrazide. Using this technique, the three-dimensional ultrastructure of interphase nuclei and mitotic chromosomes was examined. In Interphase, different levels of chromatin condensation were observed, consisting of fibrils 10 nm in diameter, 20- to 40-nm fibres and a higher order complex. In prophase, globular and strand-like structures composed of 20- to 40-nm fibres were dominant. As the cells progressed through the cell cycle and the chromatin condensed, globular and strand-like structures (chromomeres) were coiled and packed to form chromosomes. Chromomeres were observed as globular protuberances on the surface of metaphase chromosomes. These findings indicate that the chromomere is a fundamental substructure of the higher order architecture of the chromosome. In the centromeric region, there were no globular protuberances, but 20- to 40-nm fibres were folded compactly to form a higher level organization surrounding the chromosomal axia.

Highly conserved 5'-flanking regions of two self-incompatibility genes, SLG9 and SRK9

The nucleotide (nt) sequences of the 5'-flanking regions of two Brassica self-incompatibility genes, SLG9 and SRK9, were determined. Their sequences were highly conserved: a region spanning 1.9 kb in the 5'-flanking region was completely identical except for a 1319-bp segment in SLG9. These observations strongly suggest that SLG9 and SRK9 together with their promoter regions were involved in a gene duplication or conversion event which occurred before the 1319-bp SLG9-specific sequence was inserted in SLG9 or deleted in SRK9.

Aflastatin A, a novel inhibitor of aflatoxin production by aflatoxigenic fungi

Aflastatin A, a novel inhibitor of the production of aflatoxin by aflatoxigenic fungi, has been isolated from the solvent extract of mycelial cake of Streptomyces sp. and its molecular formula was determined as C62H115NO24. Aflastatin A completely inhibited aflatoxin production by Aspergillus parasiticus NRRL 2999 in liquid medium or on agar plate at a concentration of 0.5 microgram/ml. The mycelial growth of this fungus was not affected in the liquid medium at the same concentration, while the hyphal extension rate was reduced on the plate together with some morphological changes. The growth of the fungus was not completely inhibited even at a concentration of 100 micrograms/ml. Aflastatin A exhibits antimicrobial activity against some bacteria, yeasts and fungi as well as antitumor activity.

The cessation of fluoridated water administration and the fluoride distribution profiles in rat molar cementum

The aim of this work was to obtain further information about the origin of fluoride profiles in cementum. Fluoride was administered to rats at varying doses (0.50, 100 ppm F in drinking water) and for different durations (4, 13 and 25 weeks). Fluoride distribution across the full thickness of molar cementum in rats was measured by means of an abrasive micro-sampling technique. The average fluoride concentrations in cementum increased significantly with increasing dose and duration of fluoride administration. The relative reduction of the average fluoride concentrations after cessation of fluoride administration was 94.2-36.5% at 50 ppm F and 62.2-49.2% at 100 ppm F in the outer layers (1-60 microns) and 91.5-24.1% at 50 ppm F and 74.1-7.6% at 100 ppm F in the middle (61-120 microns) layers of the cementum, respectively. The reduction rates were more closely related to the time intervals following cessation rather than fluoride concentrations in drinking water or specificity within the cementum. Two factors which may influence this are new cementum formation after withdrawal of fluoride and some fluoride release from cementum surfaces when the fluoride supply stopped. It was concluded that the cessation of fluoride administration reduced the fluoride concentration on the outer layers of cementum differing from bone where reduction occurs across the entire thickness.