TRiC-P5, a novel TCP1-related protein, is localized in the cytoplasm and in the nuclear matrix

We have recently reported the cloning of a novel protein, TRiC-P5, with significant homology with protein 1 of the t-complex (TCP1). In the present study, the cellular localization of TRiC-P5 in Raji cells has been determined using an antiserum raised against a 18.5 kDa fusion protein. Results from cell fractionation and immunoblot studies indicate that TRiC-P5 is mainly localized in the cytoplasm. In addition, a significant part of TRiC-P5 is also found in the nucleus where it is attached to the nuclear matrix, a complex filament network involved in essential cellular functions such as DNA replication, and RNA transcription and maturation. Immunofluorescence experiments using the anti-TRiC-P5 antibodies confirm these results. We also provide evidence that, in the cytoplasm, TRiC-P5 is part of a large protein complex, most probably the TCP1-ring complex (TRiC), a hetero-oligomeric ring complex that plays a role of molecular chaperone in the folding of actin and tubulin.

A single mutation of the fumarylacetoacetate hydrolase gene in French Canadians with hereditary tyrosinemia type I

BACKGROUND

Hereditary tyrosinemia type I is an autosomal recessive inborn error of metabolism caused by a deficiency of the enzyme fumarylacetoacetate hydrolase. The disorder clusters in the Saguenay-Lac-St.-Jean area of Quebec. In this region, 1 of 1846 newborns is affected and 1 of every 22 persons is thought to be a carrier. Recently, we identified a splice mutation and two nonsense mutations in the fumarylacetoacetate hydrolase gene in two patients from Quebec with tyrosinemia type I.

METHODS

We used allele-specific-oligonucleotide hybridization to examine the frequency of these three candidate mutations in patients with tyrosinemia type I and in the population of Quebec.

RESULTS

The splice mutation was found in 100 percent of patients from the Saguenay-Lac-St.-Jean area and in 28 percent of patients from other regions of the world. Of 25 patients from the Saguenay-Lac-St.-Jean region, 20 (80 percent) were homozygous for this mutation, a guanine-to-adenine change in the splice-donor sequence in intron 12 of the gene, indicating that it causes most cases of tyrosinemia type I in the region. The frequency of carrier status, based on screening of blood spots from newborns, was about 1 per 25 in the Saguenay-Lac-St.-Jean population and about 1 per 66 overall in Quebec.

CONCLUSIONS

This study identified the most prevalent mutation causing hereditary tyrosinemia in French Canada; it also showed the feasibility of DNA-based testing for carriers in the population at risk.

Hereditary tyrosinemia type I: strong association with haplotype 6 in French Canadians permits simple carrier detection and prenatal diagnosis

Hereditary tyrosinemia type 1 (HT1), a severe inborn error of tyrosine catabolism, is caused by deficiency of the terminal enzyme, fumarylacetoacetate hydrolase (FAH). The highest reported frequency of HT1 is in the French Canadian population, especially in the Saguenay-Lac-St-Jean region. Using human FAH cDNA probes, we have identified 10 haplotypes with TaqI, KpnI, RsaI, BglII, and MspI RFLPs in 118 normal chromosomes from the French Canadian population. Interestingly, in 29 HT1 children, a prevalent haplotype, haplotype 6, was found to be strongly associated with the disease, at a frequency of 90% of alleles, as compared with approximately 18% in 35 control individuals. This increased to 96% in the 24 patients originating from Saguenay-Lac-St-Jean. These results suggest that one or only a few prevailing mutations are responsible for most of the HT1 cases in Saguenay-Lac-St-Jean. Since most patients were found to be homozygous for a specific haplotype in this population, FAH RFLPs have permitted simple carrier detection in nine different informative HT1 families, with a confidence level of 99.9%. Heterozygosity rate values obtained from 52 carriers indicated that approximately 88% of families at risk from Saguenay-Lac-St-Jean are fully or partially informative. Prenatal diagnosis was also achieved in an American family. Analysis of 24 HT1 patients from nine countries gave a frequency of approximately 52% for haplotype 6, suggesting a relatively high association, worldwide, of HT1 with this haplotype.

Shifts in type I fiber proportion in rat hindlimb muscle are accompanied by changes in HSP72 content

Heat-shock protein 72 (HSP72), the inducible isoform of the HSP70 family, is constitutively expressed in rat hindlimb muscles in proportion to the content of type I muscle fibers. To determine whether this relationship was maintained after fiber transformation, male Sprague-Dawley rats were treated with 3,5,3'-triiodo-DL-thyronine (T3) for 40 days or underwent surgical removal of the left gastrocnemius muscle, after which the left plantaris muscle was allowed to hypertrophy for 30 days. Hypertrophied plantaris muscles exhibited an increased number of type I fibers, type I myosin heavy-chain (MHC) protein, and HSP72 content compared with contralateral muscles. Soleus muscles from rats administered T3 exhibited an increased number of type II fibers, citrate synthase activity, and decreased HSP72 content compared with soleus muscles from controls. These results indicate that the relationship between HSP72 content and type I muscle fiber-MHC composition is maintained when muscles undergo fiber transformation and substantiate that HSP72 content in rat skeletal muscle is not directly linked to a muscle's oxidative capacity.

Identification of a stop mutation in five Finnish patients suffering from hereditary tyrosinemia type I

Hereditary tyrosinemia type I is a metabolic disease caused by a deficiency of fumarylacetoacetate hydrolase (FAH, EC 3.7.1.2), the last enzyme in the catabolic pathway of tyrosine. The molecular basis of FAH deficiency was examined in five Finnish patients suffering from this severe metabolic disease. No immunoreactive FAH nor enzymatic activity were found in their liver. Direct sequencing of the 14 exons of the FAH gene showed a G to A transition, which predicts a change from tryptophan to a stop codon (TGG-->TGA) at position 262 (W262X). Four of the five patients examined were homozygous for the mutation. Allele specific oligonucleotide hybridization showed a predominance of the W262X mutation in Finland (9 of 10 alleles) and the absence of this mutant allele in patients from other parts of the world. The loss of a BsaJI restriction site in those patients may be used for diagnosis.

Rescue of mice homozygous for lethal albino deletions: implications for an animal model for the human liver disease tyrosinemia type 1

Mice homozygous for specific deletions around the albino locus on chromosome 7 die within the first few hours of birth. They have a complex phenotype in liver and kidney, which includes multiple changes in gene expression and ultrastructural abnormalities. On the basis of this phenotype, it was proposed that these deletions remove a regulatory locus, alf or hsdr-1. Recently, we and others showed that the gene for fumarylacetoacetate hydrolase (Fah), an enzyme involved in tyrosine catabolism, was disrupted by the lethal albino deletion c14CoS. The finding that the Fah gene in wild-type mice is highly expressed only in cell types that develop a phenotype in mutants, and the fact that Fah deficiency determines the human liver disease hereditary tyrosinemia type 1 (HT1), suggested that disruption of the Fah gene was responsible for the lethal albino phenotype. To test this hypothesis, we have created lines of mice carrying Fah transgenes. We find that c14CoS homozygotes which express transgenic Fah are complemented for all aspects of the complex lethal albino phenotype. Moreover, the degree to which the phenotype is corrected depends on the level of transgenic Fah expression. These results unequivocally establish Fah as the gene mapping at alf/hsdr-1 and prove that the phenotype depends ultimately on the blockage of tyrosine metabolism. Finally, they suggest lethal albino mice as an animal model for HT1.

HSP90 associates with specific heat shock puffs (hsr omega) in polytene chromosomes of Drosophila and Chironomus

The heat shock protein HSP90, which is mainly cytoplasmic, has recently been reported to be present in the nucleus. We have found a specific chromosomal localization of HSP90 in different species of Drosophila and Chironomus using immunocytochemical techniques with different mono- and polyclonal antibodies for this hsp. HSP90 was found associated with heat shock-induced puffs at 93D and 48B in salivary gland chromosomes of Drosophila melanogaster and Drosophila hydei, respectively. The localization of HSP90 to locus 93D occurred rapidly after the onset of heat shock and disappeared during recovery, concomitant with puff regression. The association of HSP90 with the 93D locus was strictly heat shock dependent as shown by the absence of HSP90 in puff 93D induced by either benzamide or colchicine. No specific nuclear staining was observed in unstressed control cells. HSP90 was also found in the temperature-induced telomeric Balbiani ring puffs (T-BRs) in Chironomus thummi and in one heat shock puff at I-1C in Chironomus tentans. Other heat shock puffs also appeared lightly stained with the HSP90 polyclonal antibody in both species of Chironomus. HSP90 was absent from the T-BRs when RNA synthesis was inhibited with Actinomycin D suggesting that the localization of HSP90 is dependent on transcription. Inhibition of protein synthesis did not prevent association of this hsp with the T-BRs, indicating that pre-existing HSP90 can associate with this locus. HSP90 did not associate with any telomeric chromosomal regions of unstressed cells. The present observations suggest that heat shock gene products such as HSP90 may somehow be involved in the regulation at the chromosomal level of other members of the heat shock gene family. Puffs 93D (D. melanogaster) and 48B (D. hydei) are equivalent and correspond to homologous gene loci (hsr omega) that have unusual features that distinguish them from other heat shock puffs. The binding of HSP90 at T-BRs and at puff I-1C in the genus Chironomus is the first demonstration, albeit indirect, of the existence of hsr omega analogous loci in species other than Drosophila.

Transcriptional and translational study of the Drosophila subobscura hsp83 gene in normal and heat-shock conditions

In this paper we report a transcriptional and translational study of the hsp83 gene of Drosophila subobscura. This gene is located at the 18C region of the J chromosome. A monoclonal antibody raised against hsp83 was used for the immunological detection of this protein by Western blotting throughout the development of D. subobscura in control and heat-shock conditions. Our results indicate that puff 18C is not only heat-shock inducible but is also expressed during normal development and its level of expression increases at the end of the prepupa period. We detected hsp83 at normal temperatures, in particular developmental stages with the exception of the larval and the beginning of prepupa formation. Hsp83 was induced by heat shock in all stages studied with the exception of 1st instar larvae. We found that temperatures in excess of 26 degrees C were sufficient to induce hsp83. In addition, at temperatures from 26 to 34 degrees C, the increase in hsp83 synthesis was accompanied by increased transcription of the hsp83 gene; this positive correlation was not observed at 37 degrees C.

Intramitochondrial localization of the main 70-kDa heat-shock cognate protein in Drosophila cells

The main heat shock cognate protein (hsc) of 70 kDa in Drosophila, hsc 4, was localized in cultured cells using a specific affinity-purified antibody and colloidal gold immunoelectron microscopy. This constitutively expressed member of the heat shock protein (hsp) 70 family is found in the cytosol, in mitochondria, and in the nucleus of unstressed cells. The identity of hsc 4 in these three cellular compartments was confirmed by two-dimensional gel immunoblots and partial proteolytic digestion patterns. In mitochondria, the colloidal gold particles are observed in close proximity to or on the inner membranes. The intramitochondrial localization of this hsc was confirmed by density gradient purification and by resistance of hsc 4 to externally added trypsin. In the nucleus, the labeling is found on nucleo-plasmic perichromatin RNP fibrils and is not detected in the nucleolus. Heat shock induces an intracellular redistribution of hsc 4 with an enrichment in the nucleus. The localization of this hsc in different cellular compartments is consistent with the previously suggested functions of some members of this family of proteins in basic cellular processes such as protein folding. Moreover, the present data suggests that the main constitutively expressed member of the hsp 70 family, hsc 4, functions both within the mitochondrial compartment and in the nucleus.

Molecular identification of onchocerciasis vector sibling species in black flies (Diptera: Simuliidae)

A number of sibling species in the Simulium damnosum species complex transmit River Blindness (onchocerciasis) in tropical Africa. Black fly sibling species can be reliably recognized only through analysis of the larval polytene chromosomes. The routine, unambiguous assignment of the potentially disease-transmitting adult females to a particular species is virtually impossible. Two molecular assays to identify the sibling species of biting female flies are presented. The first relies on PCR-mediated amplification of internal transcribed spacers of the nuclear rDNA loci while the second involves immunoblotting of silk proteins which are expressed in both larvae and adult females. Both assays yield sibling-specific size markers that can be used to identify the sibling species of biting adult females. To illustrate the use of these assays, a molecular characterization is given for two S. damnosum siblings (squamosum, sirbanum) collected from cytologically verified populations, and a partial characterization of a third sibling (damnosum s. str.) found as a contaminant in these samples.

Characterization of the human fumarylacetoacetate hydrolase gene and identification of a missense mutation abolishing enzymatic activity

Hereditary tyrosinemia type 1 is an autosomal recessive disease caused by a deficiency of the last enzyme in the catabolic pathway of tyrosine, fumarylacetoacetate hydrolase (FAH). To analyze the mutations involved in this disease, and as a first step towards elucidating the mechanisms regulating the transcription of the FAH gene, we have isolated and characterized the human gene coding for FAH. The gene contains 14 exons and spans approximately 35 kilobases of DNA. The 5' end of the gene is highly GC-rich, and eleven putative binding sites for the transcription factor Sp 1 were identified in the proximal region of the promoter. We investigated the molecular basis of FAH deficiency in a hereditary tyrosinemia type 1 patient whose liver FAH showed a very low enzymatic activity. Sequencing of the liver FAH cDNA of the patient revealed a C to A transversion in the FAH mRNA, which predicted the replacement of an alanine (A) residue with an aspartic acid (D) residue at position 134 (A134D) of the amino acid sequence of the corresponding protein. Direct sequencing of genomic DNA indicated that the patient was heterozygous for the A134D mutation. The allele that does not carry the A134D mutation was expressed at a very low level in the liver of the patient. Expression of the mutant allele in CV-1 cells confirmed that the A134D mutation was responsible for the lack of enzymatic activity in the liver of the patient.

Heat-shock response and limitation of tissue necrosis during occlusion/reperfusion in rabbit hearts

BACKGROUND

Induction of stress proteins, such as heat-shock protein 71 (HSP71), is associated with cardioprotection in isolated ischemic myocardium. We tested this hypothesis in rabbits pretreated with whole-body hyperthermia and then subjected to 30 or 45 minutes of regional coronary occlusion (CO) followed by 3 hours reperfusion (Rep).

METHODS AND RESULTS

Control rabbits did not undergo whole-body hyperthermia; heat-shocked (HS) rabbits were subjected to whole-body hyperthermia at 42 degrees C for 15 minutes. Rabbits were allowed to recover from whole-body hyperthermia for 24 or 40 hours and were then subjected to CO/Rep. Heart rate and arterial blood pressure were recorded during the experiments. Area of necrosis (tetrazolium staining) was normalized to anatomic risk zone size (microsphere autoradiography). In rabbits treated with whole-body hyperthermia and 24 hours of recovery, infarct size was significantly reduced in HS rabbits compared with control rabbits (41.2 +/- 7.8% versus 23.2 +/- 6.6%; p < or = 0.05; mean +/- SD) after 30 minutes of CO and 3 hours of Rep. Risk zone size was similar for the two experimental groups. In rabbits treated with whole-body hyperthermia and 40 hours of recovery, infarct size was similar for control and HS animals with either 30 or 45 minutes of CO (p = NS) and 3 hours of Rep. Risk zone size and area of necrosis were similar for these experimental groups. Biopsies from ischemic and nonischemic myocardium were obtained from rabbits at 24 and 40 hours after heat shock and control rabbits to verify expression of HSP71; expression was determined by Western blot analysis.

CONCLUSIONS

Our findings demonstrate a considerable increase in expression of HSP71 in myocardium from hyperthermia-treated rabbits. Infarct size was significantly reduced after 30 minutes of CO and 3 hours of Rep in hearts at 24 but not 40 hours after heat shock compared with control hearts. We conclude that heat shock-induced cardioprotection is transient and delays the onset of irreversible myocardial injury caused by ischemia.

Induction of Chinese hamster HSP27 gene expression in mouse cells confers resistance to heat shock. HSP27 stabilization of the microfilament organization

Heat shock induces in cells the development of a transient state of thermotolerance thought to result from the induction of heat shock proteins. To assess directly whether a transient overexpression of one of these proteins, HSP27, can contribute to increased cellular resistance, mouse NIH/3T3 cells were cotransfected with a plasmid containing the Chinese hamster HSP27 gene under the control of the metallothionein promoter and a plasmid containing the neo gene. Stable transfectant cell lines were selected for resistance to the antibiotic G418. Analyses of several stable transfectant cell lines indicated that expression of Chinese hamster HSP27 could be selectively induced by exposure to 3 microM CdCl2, a concentration that had no effect on the induction of the endogenous heat shock proteins (HSP). In clone 15, the level of HSP27 increased steadily during the first day of exposure to CdCl2, from a concentration of 1 microgram/mg of total protein to 7 micrograms/mg. After withdrawal of CdCl2, the level of HSP27 returned to normal within the next 5 days. Accumulation of the Chinese hamster HSP27 was accompanied by a progressive development of thermoresistance that attained a level approaching heat shock-induced thermotolerance. After CdCl2 removal, thermal resistance and HSP27 decayed in a coordinated manner. In control cells transfected with the neo gene only, increased thermoresistance was not induced by 3 microM CdCl2; in these cells, an exposure to 20 microM CdCl2 was required to induce a level of thermoresistance comparable to that induced by 3 microM CdCl2 in clone 15. Elevated expression of HSP27 was accompanied by an increased stability of stress fibers during hyperthermia. The protein also partially prevented actin depolymerization during acute exposure to cytochalasin D and reduced cytotoxicity and growth inhibition of chronic exposures to the drug. The results indicated that accumulation of HSP27, as it occurs after a mild heat shock or other inducing treatments, is sufficient for acquisition of thermotolerance that may result in part from a stabilization of actin filaments.

Localization of cells in the rat brain expressing fumarylacetoacetate hydrolase, the deficient enzyme in hereditary tyrosinemia type 1

Fumarylacetoacetate hydrolase (FAH) is the terminal enzyme in the catabolic pathway of tyrosine. This enzyme which is mainly expressed in the liver and kidney is deficient in hereditary tyrosinemia type 1. As some affected individuals present neurologic abnormalities, we studied the expression of FAH in the rat and human brain. The FAH gene was shown to be expressed in the rat brain by immunoblot and Northern blot analysis. The FAH protein was also detected in human brain by the immunoblot assay. An immunohistochemical study was undertaken to localize the FAH-producing cells in the rat central nervous system. This analysis showed that the majority of FAH-producing cells are localized in the axonal nerve fibers of the white matter, although positive cells could also be found throughout the brain. The greatest number of FAH-positive cells were found in structures consisting essentially of white matter, such as the corpus callosum. This specific localization in the white matter indicates that some type of glial cells are responsible for the expression of the FAH protein in the rat central nervous system. The characteristic linear organization found in some of the FAH-positive cells in the corpus callosum suggests that these glial cells are oligodendrocytes. These findings are discussed with respect to the neurologic symptoms observed in some tyrosinemia patients.

Effect of hydrogen peroxide on cytoskeletal proteins of Drosophila cells: comparison with heat shock and other stresses

Hydrogen peroxide, which was shown to trigger the heat-shock response by activating the immediate binding of the heat-shock factor to DNA heat shock regulatory elements in the promoter of heat-shock genes of Drosophila cells, has also been reported to enhance the synthesis of actin. We show here that very short and transient H2O2 treatments, from 1 s to 2 min, are sufficient to induce an increase of actin synthesis. This increase becomes apparent 2 to 3 h after the short H2O2 treatment. It is inhibited if actinomycin D is present during the short H2O2 treatment. An increase of actin synthesis was also observed during the recovery period after two other stresses: reoxygenation after anoxia and ethanol treatment. The synthesis of two cytoskeletal proteins, tubulin and a 46-kDa insoluble protein of the intermediate filament fraction, was also slightly increased by H2O2 in Drosophila cells, but this increase was not actinomycin D-dependent. H2O2 does not provoke the translocation of the 46-kDa protein to the nuclear fraction as does heat shock. The very rapid stimulation of actin synthesis by H2O2 and the involvement of cytoskeletal elements in many stress situations suggest that actin may play a key role in the response to external stimuli.

Tissue-specific expression of heat shock proteins of the mouse in the absence of stress

The steady-state levels of four members of the heat shock proteins families (HSP84, HSC73, HSP71, and HSP25) were examined by immunoblot analysis of several different tissues of young and adult mice in the absence of stress. These hsps were detected in all tissues but their level was variable. The levels of HSC73 and HSP84 varied only slightly between different tissues in either young or adult mice, with the exception of skin where these hsps were found in reduced amounts. In contrasts, the stress-inducible member of the HSP70 family, HSP71, was found to be expressed in all tissues but in amounts which differed by as much as two orders of magnitude between tissues. In general, the levels of both HSP71 and HSP25 were found to be tissue dependent, with higher levels found in tissues such as stomach, intestine, colon and bladder, tissues which are exposed to toxic environmental or metabolic products, and which may concentrate these substances by water resorption and/or be exposed to them for longer periods. The levels of HSP71 and HSP25 were generally positively correlated both in young and adult mice although this correlation was not found in certain tissues such as kidney, testes, and bone. Tissues of young mice contained lower amounts of HSP25 and HSP71 than were found in the same tissues from adults. We conclude that hsps are expressed in all tissues of the mouse in the absence of stress and that some organs, particularly those exposed to potentially toxic metabolites, show a higher level of expression of HSP71 and HSP25.

hsp23 and hsp26 exhibit distinct spatial and temporal patterns of constitutive expression in Drosophila adults

To determine differences in the patterns of expression of Drosophila small heat shock proteins (shsp) during normal development in the absence of stress, proteins obtained from head, thorax and gonads of young (0-12 h, 3 days), middle-aged (3-6 days) and 15- to 20-day-old adult flies were separated on SDS-PAGE gels and blotted with monoclonal antibodies against hsp23 and hsp26. hsp23 was found in the heads and gonads of young males and females. In contrast, the maximum expression of hsp26 was seen in gonads of young flies, and it was only lightly detected in the brain. The expression of both proteins decreased as flies aged. This age-related decrease was particularly striking for hsp23 in females. The immunoblot results obtained were complemented by immunostaining of thin parasagittal sections of whole fly bodies. Hsp23 was found to be expressed in the brain, thoracic ganglion, fat body and gonads of young (0-12 h) males and females. On the other hand, hsp26 was essentially detected in ovaries and testes of these young flies. The analysis of the tissue expression of both proteins demonstrate that each shsp has a distinct cellular localization. In the central nervous system, hsp23 and hsp26 were present in the neurocytes of the brain and the thoracic ganglion. In addition, hsp23 (but not hsp26) was also detected in the central neuropile of these two organs. In testis, hsp26 was localized in the cytoplasm of spermatocytes and, probably, in the spermatid bundles. In contrast, hsp23 was detected at the periphery of cells (membranes).(ABSTRACT TRUNCATED AT 250 WORDS)

Type 1 hereditary tyrosinemia. Evidence for molecular heterogeneity and identification of a causal mutation in a French Canadian patient

Type 1 hereditary tyrosinemia (HT1) is a metabolic disorder caused by a deficiency of fumarylacetoacetate hydrolase (FAH). Using a full-length FAH cDNA and specific antibodies, we investigated liver specimens from seven unrelated HT1 patients (six of French Canadian and one of Scandinavian origin). The expression of FAH in livers of these individuals was analyzed at several molecular levels including mRNA, immunoreactive material (IRM), and enzymatic activity. Four phenotypic variants were differentiated by these assays: (i) presence of FAH mRNA without any IRM or enzymatic activity, (ii) decreased FAH mRNA, IRM, and enzymatic activity, (iii) moderately decreased FAH mRNA and IRM with severely reduced enzymatic activity, and (iv) undetectable FAH mRNA, IRM, and enzymatic activity. These various molecular phenotypes suggest that this disorder may be caused by a variety of FAH mutations. Interestingly, we found no apparent relationship between the clinical and the molecular phenotypes, except that patients with absent IRM and enzymatic activity tend to have higher levels of serum alpha-fetoprotein and an earlier clinical onset. To further analyze the molecular basis of HT1, the FAH cDNA of a patient designated as variant A was amplified and sequenced. An A-to-T transversion, which substitutes asparagine16 with isoleucine (N16I), was identified. This patient was heterozygous as shown by direct sequencing of the amplified region and hybridization with allele-specific oligonucleotide probes. The N16I allele originates from the father and the second allele appears not to be expressed in the liver of the proband. CV-1 cells transfected with the mutant cDNA produced FAH mRNA, but no protein or hydrolytic activity, as predicted by the "A" phenotype of the patient. This is the first demonstration of heterogeneity in the expression of FAH at the levels of protein, mRNA, and enzymatic activity in the livers of HT1 patients and is the first identification of a causal mutationin this disease.

Isolation and sequence of a 2-kbp miniplasmid from Bacillus thuringiensis var. kurstaki HD-3a3b: relationship with miniplasmids of other B. thuringiensis strains

The miniplasmid profiles of 18 Bacillus thuringiensis strains belonging to 8 different serotypes were determined using an alkaline hydrolysis method for isolation of low molecular mass plasmids. Nearly all the strains contained covalently closed circular (CCC) DNA species ranging from 2 to 5 species per strain and from 1.5 to 10.5 kbp in size (values corresponding to CCC forms). A 2-kbp plasmid from B. thuringiensis var. kurstaki HD-3a3b futura strain was used in Southern hybridization experiments to analyse relationships among the low molecular mass plasmids of different B. thuringiensis strains. This 2-kbp miniplasmid was present in most strains which show toxicity against lepidoptera. It was not present in those strains toxic against diptera (B. thuringiensis var. israelensis) or coleoptera (B. thuringiensis var. tenebrionis). The 2-kbp miniplasmid from B. thuringiensis var. kurstaki HD-3a3b futura was cloned and fully sequenced. Sequence analysis of the 2058 bp of the miniplasmid revealed the presence of an ORF (630 bp, 210 amino acids in size) that is preceded by a consensus sequence of B. thuringiensis crystal protein gene transcription promoters. No significant homology was observed with known B. thuringiensis toxin nucleic acid sequences or with other known sequences.

Expression of Drosophila's 27 kDa heat shock protein into rodent cells confers thermal resistance

The role of hsp27, one of Drosophila melanogaster's small heat shock proteins, in the process of thermotolerance was investigated. The coding sequence of hsp27 was subcloned downstream of the human hsp27 promoter which has been shown to be constitutively expressed in Chinese hamster O23 cells. Cellular resistance to a thermal stress was measured two days after transfection by a survival assay following a 3.5 h heat treatment at 44 degrees C. Expression of Drosophila hsp27 was shown to confer thermal resistance to O23 cells in a manner which was dependent on the level of expression of this hsp. Immunoblot analysis confirmed that the thermal resistance was related to the expression of Drosophila hsp27 as none of the endogeneous hsps showed an increased level under these conditions.

MspI RFLP in the human fumarylacetoacetate hydrolase (FAH) gene

Images

Cloning and expression analysis of a cDNA encoding fumarylacetoacetate hydrolase: post-transcriptional modulation in rat liver and kidney

Fumarylacetoacetate hydrolase (FAH) is an enzyme which is deficient in human hereditary tyrosinemia type 1. We have cloned and sequenced a rat liver cDNA encoding FAH. The identity of the clone was ascertained by hybrid-selection experiments and deduced amino acid (aa) sequence homologies with sequenced oligopeptide fragments of the purified rat liver protein. The cDNA codes for a 419-aa protein of 45,946 daltons. We used this cDNA as a probe in conjunction with a specific anti-rat FAH antibody to study the expression pattern of the FAH gene in rat liver and kidney. Northern blot analysis indicates that the kidney contains slightly more FAH mRNA that the liver. Western blotting shows, however, that the liver contains about twice as much FAH protein as the kidney. Primer extension experiments suggest that there are no differences in the 5'-untranslated (UT) ends of the FAH mRNA of both tissues. We conclude that synthesis of the FAH protein is in part regulated at the post-transcriptional level in rats liver and kidney, and that this regulation does not appear to be mediated by the 5'-UT sequence of the FAH mRNA.

Analysis of RNA for transcripts for catalase and SP71 in rat hearts after in vivo hyperthermia

Hyperthermic stress induces synthesis of the major inducible (heat) stress protein (SP71) in all rat tissues. In addition, there is an increase in catalase activity in hearts at 24 and 48 h after the induction of the heat shock response. To more precisely define some of the molecular aspects of the induction of the heat shock response in hearts, we examined mRNA levels for the catalase, SP71 and HSP27. RNA was isolated from control hearts and at various time periods (0-24 h) of recovery after brief hyperthermic treatment and was analyzed by Northern blot analysis using as probes cDNA sequences for rat liver catalase, human HSP70 (inducible), and human HSP27. There was no detectable change in mRNA for catalase after heat shock or during recovery. Hyperthermic stress has no apparent effect on the regulation of transcription of mRNA coding for catalase, indicating that the increase in catalase activity is either translationally or post-translationally regulated. The human HSP70 cDNA did not hybridize to control heart RNA, but did hybridize to SP71 transcripts at 0, 1.5, and 3 h post heat shock. The mRNA level for SP71 peaked at 1.5 h, was reduced at 3 h, and became almost undetectable at 6 h post heat shock. Similarly, the human HSP27 cDNA did not hybridize to control heart RNA, but did hybridize to transcripts for HSP27 at 0, 1.5, 3, and up to 15 h post heat shock. Maximal signal for HSP27 was at 3 h post heat shock and was sharply reduced at 6 h post heat shock.(ABSTRACT TRUNCATED AT 250 WORDS)

KpnI and RsaI RFLPs for the human fumarylacetoacetate hydrolase (FAH) gene

Images