UFD2a mediates the proteasomal turnover of p73 without promoting p73 ubiquitination

p73 protein level is kept extremely low in mammalian cultured cells and its stability may be regulated by not only the ubiquitin/proteasome-dependent proteolysis but also through other unidentified mechanisms. Here, we found for the first time that p73 is physically as well as functionally associated with the U-box-type E3/E4 ubiquitin ligase UFD2a. The immunoprecipitation experiments demonstrated that this interaction is mediated by the COOH-terminal region of p73alpha containing SAM domain. During the cisplatin-induced apoptosis in SH-SY5Y neuroblastoma cells, p73alpha accumulated at a protein level, whereas the endogenous UFD2a was significantly reduced in response to cisplatin. Ectopic expression of UFD2a decreased the half-life of p73alpha in association with a significant inhibition of the p73alpha-mediated transactivation as well as proapoptotic activity. Downregulation of endogenous UFD2a by antisense strategy resulted in a remarkable accumulation of p73alpha. Unexpectedly, UFD2a-mediated degradation of p73alpha was sensitive to the proteasomal inhibitor, however, UFD2a did not affect the ubiquitination levels of p73alpha. Taken together, our present findings imply that UFD2a might promote the proteasomal turnover of p73 in a ubiquitination-independent manner, and also suggest that UFD2a might play an important role in the regulation of cisplatin-induced apoptosis mediated by p73.

Brain abscess secondary to the middle ear cholesteatoma: a report of two cases

We experienced two cases of brain abscess secondary to middle ear cholesteatoma. One, a 61-year-old woman, presented with left otalgia, appetite loss and nausea. The computed tomography obtained on admission revealed a middle ear cholesteatoma. The magnetic resonance image showed the presence of a brain abscess in the cerebellum. The brain abscess was drained and the cholesteatoma was removed using the canal down procedure under general anesthesia. Part of the cholesteatoma invaded the posterior cranial fossa was could not be removed from the otological surgical field. The patient has been under observation as an outpatient for 6 months already and no abnormal signs have been detected. The other patient, a 55-year-old man, was admitted to our hospital for a detailed examination because he had right otalgia and progressive headache. The examination of spinal fluid obtained by lumbar puncture showed marked elevation of the white blood cells count. Computed tomography revealed a middle ear cholesteatoma. The magnetic resonance image obtained on admission showed an area of low-intensity encapsulated by an area of high-intensity in the right temporal lobe. The abscess was drained and the cholesteatoma was removed using the canal down procedure under general anesthesia. The patient has been under observation for 1 year already and has presented no signs of recurrence.

1,10-Phenanthroline phosphorylates (activates) MAP kinase in Xenopus oocytes

The membrane-permeable intracellular heavy metal chelator, 1,10-phenanthroline, which prevents progesterone-induced germinal vesicle breakdown (GVBD), would be expected to regulate phosphorylation (activation) of the MAP kinase (MAPK) cascade in Xenopus oocytes. Here, our experiments show that 1,10-phenanthroline itself results in the phosphorylation of MAPK in both oocytes and a cell-free system. In contrast, 1,7-phenanthroline, the nonchelating analogue, had no effect. A supplement of zinc (as a heavy metal) given to 1,10-phenanthroline-loaded oocytes suppressed the stimulatory effects of 1,10-phenanthroline, while 1,10-phenanthroline withdrawal caused dephosphorylation of activated MAPK. Further, treatment with a MEK (a MAPK kinase) inhibitor, PD 098059 or U0126, suppressed 1,10-phenanthroline-stimulated MAPK phosphorylation, indicating that 1,10-phenanthroline can phosphorylate MAPK in a MEK-dependent fashion. Our results suggest that phosphorylation of MAPK by 1,10-phenanthroline depends on the interaction of MEK. Thus, the intracellular heavy metal (zinc) regulates MAPK phosphorylation and 1,10-phenanthroline can serve as a unique tool for investigating MAPK phosphorylation mechanism.

Two cases of plunging ranula managed by the intraoral approach

Two cases of plunging ranula are reported. Treatment consisted of the total removal of the sublingual gland and evacuation of the cystic contents by the intraoral approach. The cyst remained just after the surgery in both cases, but then gradually regressed and disappeared within two months after the surgery. These findings support total removal of the sublingual gland as being the best method of treatment. We believe that complete dissection of the cyst with cervical incision as well as drainage of the cystic contents are unnecessary when the diagnosis of the plunging ranula is confirmed.

Nuclear-factor kappa B (NF-kappa B)-inducible nitric oxide synthase (iNOS/NOS II) pathway damages the stria vascularis in cisplatin-treated mice

BACKGROUND

Cisplatin is reported to damage the stria vascularis of the cochlea. Free radicals, especially large amounts of nitric oxide catalyzed by inducible nitric oxide synthase, are considered to have an important role in this toxicity. The induction of inducible nitric oxide synthase is regulated by nuclear-factor kappa B (NF-kappa B). We examined the damage of the stria vascularis by immunohistochemical techniques.

MATERIALS AND METHODS

Cisplatin (15 mg/kg b.w.) was injected intraperitoneally into the mice. Three days after the injection, the cochleas were immunohistochemically-stained using specific antibodies for nuclear-factor kappa B (NF-kappa B), inducible nitric oxide synthase (iNOS) or single-stranded DNA.

RESULTS

NF-kappa B was expressed in the cisplatin-treated cochlea, especially in the stria vascularis and the spiral ligament. iNOS was also expressed in the stria vascularis and the spiral ligament. Fragments of DNA were observed only in the stria vascularis.

CONCLUSION

The large amounts of NO catalyzed by iNOS led to inner ear dysfunction. Our results indicate that apoptosis is triggered by iNOS and that it mediates the ototoxicity induced by cisplatin.

Identification of a distal enhancer for the melanocyte-specific promoter of the MITF gene

Waardenburg syndrome (WS) is characterized by deafness and hypopigmentation because of the lack of melanocytes in the inner ear and skin. WS type 2 is associated with mutations in the gene encoding microphthalmia-associated transcription factor (MITF) that is required for melanocyte differentiation. MITF consists of multiple isoforms with different N-termini, one of which is exclusively expressed in melanocytes, named MITF-M. Its N-terminus is encoded by exon 1M that is under the regulation of the melanocyte-specific (M) promoter. Here we identify a distal regulatory region of 298 bp, located 14.5 kb upstream from exon 1M, which enhances the M promoter activity in cultured melanoma cells. This enhancer activity depends on the proximal M promoter region (-120 to -46). The MITF-M distal enhancer (MDE), thus identified, contains the binding sites for SOX10, a transcription factor responsible for another type of WS, known as Waardenburg-Hirschsprung syndrome. Characterization of MDE has suggested SOX10 as one of factors that are involved in the function of MDE. A putative MDE counterpart is located 12 kb upstream from mouse exon 1M and its role is discussed in relevance to the pathogenesis of red-eyed white Mitf mi-rw mice that exhibit small red eyes and white coat. Moreover, by in situ hybridization analysis, we suggest that Sox10 and Mitf-M (mRNA) are expressed in melanoblasts migrating toward the otic vesicle (prospective inner ear) of mouse embryos but are separately expressed in different cell types of the newborn cochlea. Thus, SOX10 regulates transcription from the M promoter in a developmental stage-specific manner.

Regular spliceosomal introns are invasive in Chlamydomonas reinhardtii: 15 introns in the recently relocated mitochondrial cox2 and cox3 genes

In the unicellular green alga, Chlamydomonas reinhardtii, cytochrome oxidase subunit 2 (cox2) and 3 (cox3) genes are missing from the mitochondrial genome. We isolated and sequenced a BAC clone that carries the whole cox3 gene and its corresponding cDNA. Almost the entire cox2 gene and its cDNA were also determined. Comparison of the genomic and the corresponding cDNA sequences revealed that the cox3 gene contains as many as nine spliceosomal introns and that cox2 bears six introns. Putative mitochondria targeting signals were predicted at each N terminal of the cox genes. These spliceosomal introns were typical GT-AG-type introns, which are very common not only in Chlamydomonas nuclear genes but also in diverse eukaryotic taxa. We found no particular distinguishing features in the cox introns. Comparative analysis of these genes with the various mitochondrial genes showed that 8 of the 15 introns were interrupting the conserved mature protein coding segments, while the other 7 introns were located in the N-terminal target peptide regions. Phylogenetic analysis of the evolutionary position of C. reinhardtii in Chlorophyta was carried out and the existence of the cox2 and cox3 genes in the mitochondrial genome was superimposed in the tree. This analysis clearly shows that these cox genes were relocated during the evolution of Chlorophyceae. It is apparent that long before the estimated period of relocation of these mitochondrial genes, the cytosol had lost the splicing ability for group II introns. Therefore, at least eight introns located in the mature protein coding region cannot be the direct descendant of group II introns. Here, we conclude that the presence of these introns is due to the invasion of spliceosomal introns, which occurred during the evolution of Chlorophyceae. This finding provides concrete evidence supporting the "intron-late" model, which rests largely on the mobility of spliceosomal introns.

Temporal change of hippocampal enkephalin and dynorphin mRNA following trimethyltin intoxication in rats: effect of anticonvulsant

Trimethyltin (TMT), an organic metal, has been known to induce behavioral abnormalities including seizures and aggression. We administered TMT to rats, then, behavioral changes as well as the changes of dynorphin and Met-enkephalin mRNA were observed with or without phenobarbital treatment in order to reveal the role of neuropeptides in seizure-generating mechanisms. Met-enkephalin mRNA was significantly increased at the 2nd to 6th day after TMT administration when seizure was frequently observed. Meanwhile, dynorphin mRNA was decreased significantly from the 2nd day to 16th day during aggression score remained high. Phenobarbital abolished not only seizures and aggression, but also the changes of neuropeptide expressions. These results suggest that the changes of dynorphin mRNA are more strongly associated with aggression than seizures, while Met-enkephalin changes correlate more with seizures.

Acute and repeated administration of the selective 5-HT(2A) receptor antagonist M100907 significantly alters the activity of midbrain dopamine neurons: an in vivo electrophysiological study

We examined the effect of the acute and repeated administration of M100907 (formerly MDL 100907), a selective 5-HT(2A) receptor antagonist, on spontaneously active dopamine (DA) neurons in the substantia nigra pars compacta (SNC) and ventral tegmental area (VTA) of rats. This was accomplished using in vivo, extracellular single unit recording. The i.v. administration of M100907 (0.01-0.64 mg/kg) did not significantly alter the basal firing rate or pattern of spontaneously active SNC and VTA DA neurons. A single injection of either 0.01 or 0.03 mg/kg i.p. of M100907 did not significantly alter the number of spontaneously active DA neurons in either the SNC or VTA areas. However, 0.1 mg/kg i.p. of M100907 significantly increased the number of spontaneously active SNC and VTA DA neurons compared to vehicle-treated animals. A single injection of all doses of M100907 significantly decreased the degree of bursting in VTA DA neurons, whereas the 0.1 mg/kg dose increased the degree of bursting in SNC DA neurons. The repeated administration (one injection per day for 21 days) of 0.03 and 0.1 mg/kg i.p. of M100907 produced a significant decrease in the number of spontaneously active SNC and VTA DA neurons compared to vehicle-treated animals. The repeated administration of M100907 did not significantly alter the firing pattern of VTA DA neurons but significantly altered the firing pattern of SNC DA neurons. The results of this study indicate that M100907 administration alters the activity of midbrain DA neurons in anesthetized rats.

Evolutionary relationship between dinoflagellates bearing obligate diatom endosymbionts: insight into tertiary endosymbiosis

The marine dinoflagellates Peridinium balticum and Peridinium foliaceum are known for bearing diatom endosymbionts instead of peridinin-containing plastids. While evidence clearly indicates that their endosymbionts are closely related, the relationship between the host dinoflagellate cells is not settled. To examine the relationship of the two dinoflagellates, the DNA sequences of nuclear small-subunit rRNA genes (SSU rDNA) from Peridinium balticum, Peridinium foliaceum and one other peridinin-containing species, Peridinium bipes, were amplified, cloned and sequenced. While phylogenetic analyses under simple models of nucleotide substitution weakly support the monophyly of Peridinium balticum and Peridinium foliaceum, analyses under more sophisticated models significantly increased the statistical support for this relationship. Combining these results with the similarity between the two endosymbionts, it is concluded that (i) the two hosts have the closest sister relationship among dinoflagellates tested, (ii) the hypothesis that the diatom endosymbiosis occurred prior to the separation of the host cells is most likely to explain their evolutionary histories, and (iii) phylogenetic inferences under complex nucleotide evolution models seem to be able to compensate significant rate variation in the two SSU rDNA.

Detection of single-stranded DNA in the hydropic vestibule after the direct injection of antigen into the endolymphatic sac of guinea pigs

Immunohistochemical study for single-stranded DNA (ssDNA) with vestibule of guinea pigs was performed after the injection of keyhole limpet hemocyanin (KLH) into the right endolymphatic sac. Endolymphatic hydrops became evident by expansion of the Reissner's membrane in the cochlea of all animals 1 day after the injection of KLH. Increased ssDNA expression was detected in the sensory epithelium and transitional area, while temporal bones in the control group did not show any ssDNA immunoreactivities. ssDNA is accompanied with the apoptotic change in the vestibule. Our results suggest that apoptotic changes could be involved in the hydropic vestibule and these phenomena lead inner ear disturbance as seen in endolymphatic hydrops.

Distribution of cognates of group II introns detected in mitochondrial cox1 genes of a diatom and a haptophyte

We identified group IIA introns that contain an open reading frame (ORF) in the mitochondrial cytochrome oxidase subunit I (cox1) genes of yellow algae, a diatom Thalassiosira (Th.) nordenskioeldii CCMP 992 collected from the east coast of USA, and a haptophyte Pavlova (Pa.) lutheri CCMP 1325 collected from Finland. Cognate introns of CCMP 1325 were detected in all Pa. lutheri strains investigated, which were collected from various oceans. In contrast, the intron was absent from closely related species belonging to the same genus Pavlova. This was also the case for the group II intron detected in a diatom Th. nordenskioeldii CCMP 992. The group II intron of CCMP 992 was located at the corresponding site to the group IIA intron found in Pylaiella (synonym, Pilayella) littoralis. The deduced secondary structures of these introns, one of which is from a diatom and the other from a brown alga, were virtually identical. In contrast, the haptophyte group II intron was inserted at a novel locus, and shares no particularly high sequence homology with any intron known to date. The phylogenetic tree based on the intronic ORF domain was not congruent with that based on the cox1 exon. The most prominent property of the intronic ORF tree was that introns located at homologous sites made robust pair clades irrespective of the phylogenetic relationships of the organisms. This suggests that mitochondrial group II introns often invade intronless alleles across the species barrier with site specificity. Homology analysis of the haptophyte intronic ORF suggested that it comprises three domains: reverse transcriptase (RT), RNA maturase (Ma), and H-N-H endonuclease. However, the intronic ORF of the diatom contains the Ma domain but is apparently missing the H-N-H domain, and its RT domain is most probably partly or completely lacking in function.

Selection of brood stock candidates of barfin flounder using an ELISA system with recombinant protein of barfin flounder nervous necrosis virus

Barfin flounder nervous necrosis virus (BFNNV), the causative agent of viral nervous necrosis (VNN) of barfin flounder, is vertically transmitted from spawners to larvae. In the present study, an ELISA with a recombinant protein of BFNNV was performed for the detection of antibodies against BFNNV and applied for the selection of brood fish in order to prevent viral vertical transmissions. Brood stocks were divided into 4 groups based on ELISA antibody titers (< or = 10, 20, 40 and >40), and the BFNNV status of the brood stocks was determined by PCR. BFNNV was detected from the brood fish in the group with an antibody titer of >40 but not from those with titers < or = 10, 20 and 40. The offspring obtained from PCR-negative brood fish pairs in each group of ELISA antibody titers were subsequently reared for observation of VNN occurrence. VNN occurred in juveniles from 2 of 9 pairs of spawners with an antibody titer > or = 40, but did not occur in spawners with an antibody titer of < or = 10. Therefore, it was concluded that selection of brood fish using both the PCR test and ELISA antibody titers could help prevent vertical transmission of BFNNV in larval production of barfin flounder.

Nitric oxide synthase inhibitor suppresses the ototoxic side effect of cisplatin in guinea pigs

Cisplatin is known to cause inner ear damage (ototoxicity). The role of inducible nitric oxide synthase (iNOS) in the cochlea of guinea pigs after injections of cisplatin or a combination of cisplatin and NOS inhibitor (NG-nitro-L-arginine methyl ester, L-NAME) i.p. was examined electro-and immunohistochemically. The auditory brain stem responses (ABR) were measured prior to injection and 3 days after the injection. Three days after injection, the cochleas were examined immunohistochemically for iNOS. We found that iNOS was expressed in the cisplatin- and L-NAME/ cisplatin-treated cochlea. The threshold shift of ABR was significant in the cisplatin group, whereas it was decreased in the L-NAME/cisplatin group. iNOS catalyzed high NO levels lead to inner ear dysfunction. Our results indicate that iNOS mediates the ototoxicity of cisplatin.

Phylogenetic analysis of diatom coxI genes and implications of a fluctuating GC content on mitochondrial genetic code evolution

In order to address the relationships among diatom groups and to investigate possible changes in their mitochondrial (mt) genetic codes, we have analyzed a 1.1-kb region of the cytochrome c oxidase subunit I (coxI) gene from eight diverse diatom species. A phylogenetic analysis of these coxI sequences including representative species of the Phaeophyta, Xanthophyta, Eustigmatophyta and Haptophyta showed that the diatoms (Bacillariophyta) formed a well-supported monophyletic group. Of the eight species investigated, four have been classified together as radial centric diatoms based on morphology. However, in our coxI tree, the two radial centrics belonging to the order Thlassiosirales (Skeletonema costatum and Thalassiosira nordenskioldii) were placed as the sister group to the multipolar centric diatoms, while the other two radial centrics (Melosira ambigua and Rhizosolenia setigera) were in another clade. Also, in two species of the Tharassiosirales we found UGA codons that occur at conserved tryptophan (Trp) sites in the coxI sequences, strongly indicating that UGA codes for Trp in these diatoms. No evidence of a deviant genetic code was detected in the other analyzed diatom species. There was no apparent relationship between the nucleotide third-position GC content of mtDNA (based on the sequenced coxI region) and the presence of a deviant genetic code.

Mitochondrial genes are found on minicircle DNA molecules in the mesozoan animal Dicyema

Animal mitochondrial DNA genomes are generally single circular molecules, 14-20 kb in size, containing a number of functional RNAs and 13 protein-coding genes. Among these, the COI, COII and COIII genes encode three subunits of cytochrome c oxidase. We have isolated and characterized these three mitochondrial genes from the mesozoan Dicyema, a primitive multicellular animal. Surprisingly, the COI, COII and COIII genes are encoded on three small, separate circular DNA molecules (minicircles) of length 1700, 1599 and 1697 bp, respectively. We estimated the copy number of each minicircle at 100 to 1000 per cell, and have shown a mitochondrial localization of the minicircles by in situ hybridization. Furthermore, we could not detect a putative "maxicircle" DNA molecule containing any combination of the COI, COII and COIII genes using either PCR or genomic Southern hybridization. Thus, our results show a novel mitochondrial genome organization in the mesozoan animal Dicyema.

Directionally evolving genetic code: the UGA codon from stop to tryptophan in mitochondria

For the comprehensive analyses of deviant codes in protistan mitochondria (mt), we sequenced about a 1.1-kb region of a mitochondrial (mt) gene, the cytochrome c oxidase subunit I (coxI) in two chlorarachniophytes, the filose amoeba Euglypha rotunda, the cryptomonad Cryptomonas ovata, the prymnesiophyte (haptophyte) Diacronema vlkianum (Pavlovales), and the diatom Melosira ambigua. As a result of this analysis, we noticed that the UGA codon is assigned to tryptophan (Trp) instead of being a signal for translational termination in two chlorarachniophytes and in E. rotunda. The same type of deviant code was reported previously in animals, fungi, ciliates, kinetoplastids, Chondrus crispus (a red alga), Acanthamoeba castellanii (an amoeboid protozoon), and three of the four prymnesiophyte orders with the exception of the Pavlovales. A phylogenetic analysis based on the COXI sequences of 56 eukaryotes indicated that the organisms bearing the modified code, UGA for Trp, are not monophyletic. Based on these studies, we propose that the ancestral mitochondrion was bearing the universal genetic code and subsequently reassigned the codon to Trp independently, at least in the lineage of ciliates, kinetoplastids, rhodophytes, prymnesiophytes, and fungi. We also discuss how this codon was directionally captured by Trp tRNA.

Distinctive origins of group I introns found in the COXI genes of three gree algae

Upon surveying the cytochrome c oxidase subunit I (COXI) gene of green algae, we found group I introns in three species of algae, Chlorella vulgaris (Cv), Scenedesmus quadricauda (Sq) and Protosiphon botryoides (Pb). The comparative analysis of these nucleotide sequences and their secondary structures revealed that the introns of Cv, Sq, and Pb belong to groups IB1, ID, and IB2, respectively. Each of the three introns contained an open reading frame (ORF) that showed a similarity to the sequence of the LAGLIDADG endonuclease family. However, each of the intronic ORFs in Sq and Pb had a discontinuity in the middle of' the sequences coding for the LAGLIDADG endonuclease. Either of the two ORFs could be restored to a sequence homologous to the LAGLIDADG endonuclease by the insertion of a nucleotide in the appropriate position. In Sq, a putative pseudo-knot structure was detected in the intronic ORF This suggests the occurrence of a ribosomal frameshift in the translation of the ORF. because such pseudo-knot structures are common in viral ORFs employing a (-1) ribosomal frameshift. In the phylogenetic tree that was inferred from the amino acid sequences of algal and non-algal intronic ORFs, the three algal ORFs did not make a cluster, but were scattered throughout the tree. In addition. each of the three algal ORFs showed a close relationship to the ORFs of non-algal introns that were inserted at the corresponding site of the COX] gene, suggesting distinctive origins of the three algal introns via independent horizontal transfers.

Evaluation of the thoracodorsal artery as an alternative conduit for coronary bypass

Complete coronary revascularization using arterial grafts has been performed recently because of their improved patency rates. However, as the need to repeat coronary bypass surgery has become more frequent, it can be difficult to find adequate conduits for further bypass surgery. Therefore, we investigated the use of the left thoracodorsal artery (LTDA) as an alternative bypass conduit. The length from its origin, internal diameter, and number and location of branches were angiographically measured in 16 patients, and in situ blood flow volume and external diameter were intraoperatively measured in 8. Moreover, each specimen of the LTDA, the internal thoracic artery (ITA), and the inferior epigastric artery (IEA) were evaluated histologically. We found that the thoracodorsal artery has the same diameter as the ITA angiographically, and the same histological findings as the IEA. In conclusion, the thoracodorsal artery may be useful as a coronary arterial graft.