Protease and virulence of the extracellular products produced by Vibrio carchariae after growth on various media

Protease and virulence of the extracellular products (ECP) of Vibrio carchariae strain EmI82KL, a causative agent of gastroenteritis in Epinephelus coioides, cultured on different media were studied. The bacteria grown on peptone agar, nutrient agar or brain heart infusion agar produced higher protease activities than that grown on tryptic soy agar (TSA) in terms of protein content. The addition of ethylenediamine di(o-hydroxyphenylacetic acid) or horse serum in TSA enhanced the ECP protease production while the addition of grouper serum apparently reduced the enzyme activity indicating the presence of protease inhibitor(s) in the fish serum. Furthermore, the use of grouper meat or peptone as a single nutrient source remarkably enhanced the production of ECP protease. Adding proteinaceous materials from animal sources (horse serum, grouper meat or peptone) on agar manifested higher ECP protease activity than that from plant source (TSA), indicating the intestine of carnivorous groupers might favour the existence, survival or infection of the bacterium. The protease was a metal-chelator-sensitive serine protease since it was inhibited by 3,4-dichloroisocoumarin and phenylmethanesulfonyl fluoride while about 80% of its activity inhibited by chelating agents (ethylene-diaminetetraacetic acid and ethylene glycol-bis(beta-amino-ethylether) N,N,N',N'-tetraacetic acid). The ECP obtained from each medium was not lethal to the groupers suggesting that the bacterium is low virulent. As grouper is carnivorous, therefore, the role of the protease played in the fish intestine probably is competing for nutrients and/or associated with the cause of edema leading to gastroenteritis.

Allelotype analysis of uterine leiomyoma: localization of a potential tumor suppressor gene to a 4-cM region of chromosome 7q

Uterine leiomyoma is a benign smooth muscle tumor of the myometrium and is the most commonly encountered neoplasm in women of reproductive age. As for most benign tumors, the pathogenesis of leiomyoma remains obscure, especially at the molecular genetic level. The purpose of this study was to perform a genome-wide allelotype analysis to identify potential sites of tumor suppressor gene inactivation. Fifty-two cases of uterine leiomyoma were subjected to allelotype analysis by using matched pairs of tumor and blood DNA. Loss of heterozygosity (LOH) was assessed at 61 microsatellite markers distributed throughout the genome and representing all 41 chromosome arms. In general, LOH was very rare except on chromosome 7q, where LOH was observed in 34% of all informative tumors. Fine-deletion mapping with 25 microsatellite markers from the 7q22 region revealed a minimal deletion unit of approximately 4 cM, bounded by the markers D7S2453 proximally and D7S496 distally, that probably harbors a novel tumor suppressor gene involved in the etiology of this tumor.

Effects of extracellular products of Vibrio vulnificus on Acanthopagrus schlegeli serum components in vitro and in vivo

A Vibrio strain Ls001, originally isolated from a body surface lesion of a moribund black porgy (Acanthopagrus schlegeli) in 1994 in Taiwan, was identified as Vibrio vulnificus. The extracellular products (ECP) of the strain were lethal to the fish, and its effects on fish serum in vitro and in vivo are described in the present study. Nine major precipitation arcs were visualized in normal fish serum in a crossed immunoelectrophoresis (CIE) gel using rabbit antiserum to the fish normal serum and staining with Coomassie brilliant blue. Only four and six of the nine major arcs could be tentatively identified by CIE following in vivo and in vitro ECP treatment, respectively. The same two major arcs were both missing following either in vivo or in vitro treatment with ECP. These complex events may significantly contribute to the pathogenesis of V. vulnificus in A. schlegeli.

Suppression of C/EBPalpha and induction of C/EBPbeta by 2,3,7,8-tetrachlorodibenzo-p-dioxin in mouse adipose tissue and liver

We examined the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on two transcription factors, CAAT/enhancer binding protein-alpha (C/EBPalpha) and beta (C/EBPbeta), involved in the coordination of gene expression in adipose and liver. A single dose of TCDD (100 microg/kg) to male C57BL mice resulted in a time- and dose-dependent decrease in the level of C/EBPalpha mRNA in adipose tissue and liver, and a reciprocal increase in C/EBPbeta mRNA. Gel shift analysis using hepatic nuclear extracts from control and TCDD-treated mice and an oligonucleotide containing a C/EBP recognition element revealed a time-dependent change in DNA-protein complexes formed. Bands corresponding to C/EBPalpha, as determined by supershift analysis, diminished in TCDD-treated animals over a 7-day time period, whereas two new bands corresponding to C/EBPbeta, not present in control extracts, were increased significantly in treated samples. TCDD induced C/EBPbeta mRNA in wild-type mouse hepatoma cells, but not in aryl hydrocarbon receptor (AhR) nuclear translocator-deficient hepatoma cells. Induction in wild-type hepatoma cells was antagonized effectively by a molar excess of alpha-naphthoflavone. These results showed that TCDD caused rapid, reciprocal changes in C/EBPalpha and C/EBPbeta mRNAs and DNA binding in the adipose and liver of male C57BL mice and induced C/EBPbeta in hepatoma cells in an AhR-dependent manner. C/EBPs play vital roles in the coordination of energy homeostasis, and their alteration by TCDD may provide insight into the mechanism by which TCDD perturbs energy storage and utilization in vivo.

Coding sequence and exon/intron organization of the canine CLN3 (Batten disease) gene and its exclusion as the locus for ceroid-lipofuscinosis in English setter dogs

Hereditary ceroid-lipofuscinosis in English setters has been proposed to be the canine equivalent of human juvenile ceroid-lipofuscinosis, which results from defects in the CLN3 gene. Analyses were performed to determine whether the disease in English setters is also the consequence of a CLN3 gene mutation. Canine CLN3 cDNA was found to contain a 1,314-bp open reading frame predicting a derived amino acid sequence which is 89%, 85%, and 84% identical to the predicted amino acid sequences for the human, mouse, and rabbit CLN3 proteins, respectively. The canine gene has sixteen exons. No differences were detected when cDNA nucleotide sequences from an English setter with ceroid-lipofuscinosis and from a normal dog were compared. Moreover, alleles of the canine CLN3 gene distinguished by an intragenic marker segregated independently from the disease in an English setter family, eliminating CLN3 as the locus for the canine disease. A ceroid-lipofuscinosis-affected Tibetan terrier was homozygous for a Gly70Glu CLN3 variant; however, this allele is common in dog breeds considered free of ceroid-lipofuscinosis.

Susceptibility of different isolates of Vibrio harveyi to antibiotics

The susceptibility of six Vibrio harveyi strains to antibiotics was studied. Four strains originally isolated from diseased penaeids and two reference strains originally isolated from either sea water (ATCC 25919) or diseased Talorchestia sp. (ATCC 14126) were used in the present study. Results revealed that all three strains isolated in Taiwan exhibited resistance against nitrofurantoin, novobiocin and sulphonamide. The two reference strains and the strain isolated in Indonesia were susceptible to these three antibiotics.

Protein chaperones and the heat shock response in Saccharomyces cerevisiae

Recent studies have shed new light on the complexities of the heat shock response in yeast. Multiple pathways for transcriptional induction of both classic and novel heat shock proteins are emerging together with a more detailed understanding of the interactions between protein chaperones and their physiological targets. New roles for heat shock proteins in defense and recovery from the impacts of thermal stress on critical cellular processes have expanded our understanding of these elaborate and ubiquitous proteins.

Inhibition of cyclin D1 expression and phosphorylation of retinoblastoma protein by phosmidosine, a nucleotide antibiotic

In this report, we studied the effect of phosmidosine, a proline-containing nucleotide on the serum-induced cell cycle progression in human lung fibroblast WI-38 cells. Phosmidosine suppressed S-phase entry and arrested cell cycle progression at the G1 phase. In serum-stimulated cells, phosmidosine did not affect the activation of the mitogen-activated protein kinase cascade. However, phosmidosine inhibited hyperphosphorylation of retinoblastoma (RB) protein by RB-kinases such as cyclin-dependent kinase 4 and cyclin-dependent kinase 2, probably as a result of the inhibition of cyclin D1 expression. Furthermore, in tsFT210 cells, a temperature-sensitive cdc2 mutant isolated from the mouse mammary carcinoma cell line FM3A, phosmidosine, irreversibly inhibited the cell cycle progression at G1 without affecting the G2 to M transition. Phosmidosine acts at an earlier point in G1 compared with mimosine or aphidicolin, well-known cell cycle blockers at the G1-S boundary. Taken together, phosmidosine arrested cells at a specific point between the start point and restriction point in G1 and is a useful drug that may contribute to the understanding of the regulatory mechanisms of G1 progression.

Conservation of a stress response: human heat shock transcription factors functionally substitute for yeast HSF

Heat shock factors (HSF) are important eukaryotic stress responsive transcription factors which are highly structurally conserved from yeast to mammals. HSFs bind as homotrimers to conserved promoter DNA recognition sites called HSEs. The baker's yeast Saccharomyces cerevisiae possesses a single essential HSF gene, while distinct HSF isoforms have been identified in humans. To ascertain the degree of functional similarity between the yeast and human HSF proteins, human HSF1 and HSF2 were expressed in yeast cells lacking the endogenous HSF gene. We demonstrate that human HSF2, but not HSF1, homotrimerizes and functionally complements the viability defect associated with a deletion of the yeast HSF gene. However, derivatives of hHSF1 that give rise to a trimerized protein, through disruption of a carboxyl- or aminoterminal coiled-coil domain thought to engage in intramolecular interactions that maintain the protein in a monomeric state, functionally substitute for yeast HSF. Surprisingly, hHSF2 expressed in yeast activates target gene transcription in response to thermal stress. Moreover, hHSF1 and hHSF2 exhibit selectivity for transcriptional activation of two distinct yeast heat shock responsive genes, which correlate with previously established mammalian HSF DNA binding preferences in vitro. These results provide new insight into the function of human HSF isoforms, and demonstrate the remarkable functional conservation between yeast and human HSFs, critical transcription factors required for responses to physiological, pharmacological and environmental stresses.

Immunochemical localization of the Batten disease (CLN3) protein in retina

PURPOSE

Batten disease, also known as juvenile ceroid-lipofuscinosis and CLN3, is an autosomal recessively inherited disorder that results in blindness due to retinal degeneration. The CLN3 gene has been identified, but the function of the protein that this gene encodes is unknown. Experiments were conducted to determine where the CLN3 protein is localized in the mouse retina. Localization should provide a clue in evaluating potential functions of this protein.

METHODS

Using oligonucleotide primers based on the reported human CLN3 cDNA sequence, the mouse cDNA nucleotide sequence was determined from products of the reverse transcriptase-polymerase chain reaction and 3' rapid amplification of cDNA ends. A synthetic 20-amino-acid peptide corresponding to an internal hydrophilic region of the predicted amino acid sequence of the mouse CLN3 protein was used to immunize rabbits. The resulting antiserum was used in immunoblot analysis of mouse retina homogenates and in electron microscopic immunocytochemical labeling of mouse retina sections.

RESULTS

The peptide antibody labeled a single protein band of approximately 50 kDa on immunoblots of mouse retina homogenates. No labeling was detected with homogenates from human retinas. The antibody specifically labeled mitochondria of Müller cells and inner retinal neurons. Little labeling was observed in mitochondria of the photoreceptor cells. Mitochondria of other cell types, including the retinal pigment epithelium and choroidal cells, were not labeled.

CONCLUSIONS

The retinal CLN3 protein appears to be localized almost exclusively in the mitochondria, but was detected only in certain cell types. Batten disease is characterized by massive lysosomal accumulations of a small inner mitochondrial membrane protein (subunit c of ATP synthase). The mitochondrial localization of the CLN3 protein suggests that it may play a role in the normal processing of subunit c.