Emanuel Yakobson | Weizmann Institute of Science (original) (raw)
Papers by Emanuel Yakobson
Journal of Virology
The synthesis of vaccinia virus-induced thymidine kinase is normally arrested several hours after... more The synthesis of vaccinia virus-induced thymidine kinase is normally arrested several hours after infection. In thymidine kinase-deficient LM cells infected with IHD strain of vaccinia virus, arrest occurs whether or not viral DNA synthesis is inhibited. With virus inactivated by UV irradiation, enzyme synthesis takes place, but arrest is abolished. It is suggested that an early viral genetic function is responsible for the cessation of thymidine kinase synthesis.
Israel journal of medical sciences
Journal of virology, 1972
Acetone added to the maintenance medium in a 1% concentration reduces the yield of infectious rab... more Acetone added to the maintenance medium in a 1% concentration reduces the yield of infectious rabbitpox virus in L-cell monolayer cultures by 90 to 97%. This concentration of the inhibitor is not toxic for cells. It was established that there is an inhibitor-sensitive stage late in the infectious cycle. Acetone exerted no significant influence on production of early viral messenger ribonucleic acid, formation of polyribosomes, deoxyribonucleic acid (DNA) replication, or protein synthesis. In the presence of acetone, the assembly of so-called "acetone particles" occurred. These particles are similar to normal virions by morphological and sedimentation properties but are slightly different from them in buoyant density. The amount of virus-specific DNA and the optical density of the "acetone particles" are the same as those of normal virions despite a 10- to 25-fold difference in the infectivity of the preparations.
Journal of virology, 1972
Five to seven minutes after addition of (14)C-amino acids to poliovirus-infected MiO cells, radio... more Five to seven minutes after addition of (14)C-amino acids to poliovirus-infected MiO cells, radioactivity is found only in 5S virus-specific structures. With increased time of labeling, radioactivity appears in considerable amounts also in the 14S area. In the presence of guanidine blocking the transition of 14S particles in subsequent structures in MiO cells, radioactivity is first detected in the 5S zone and then accumulates predominantly in 14S particles. These results indicate that formation of 5S particles and conversion of a part of their protein into 14S particles reflect the earliest stages of the morphogenesis of poliovirus. In contrast to poliovirus-infected HeLa cells, no 73S particles could be detected in MiO cells, nor could 73S structures be detected in poliovirus-infected MiO cells after a short incubation period (20 to 30 min) with radioactive amino acids, although formation of 150S virions was observed. Addition of guanidine to infected MiO cells leads to accumulati...
Journal of virology, 1971
Poliovirus-specific structures with sedimentation constants of 5, 14, 73, and 150S produced in in... more Poliovirus-specific structures with sedimentation constants of 5, 14, 73, and 150S produced in infected HeLa cells possess different antigenic specificities.
Journal of virology, 1970
Investigation of 15 poliovirus temperature-sensitive (ts) mutants by using physiological tests [f... more Investigation of 15 poliovirus temperature-sensitive (ts) mutants by using physiological tests [formation of virus-specific antigen and ribonucleic acid (RNA) under nonpermissive conditions] permitted us to divide them into three groups. From each group, one mutant was selected (ts 2, 5, 11), and a comparative study of poliovirus-related particle (5, 10, 73, and 150S) formation under permissive (36 C) and nonpermissive (40 C) conditions was carried out. The ts 2 and ts 11 are mutants with greatly reduced RNA synthesis which at 40 C produce particles with a sedimentation constant of 5S, and the ts 5 (RNA(+)) mutant produces both 5 and 10S particles. The relationship between different temperature-sensitive defects in the mutants is discussed. The results obtained indicate a possible role of 5S protein structures in morphogenesis of poliovirus.
Journal of Dairy Science, 2011
Two-plated self-piercing eartags were first developed in the 19th century, but information on the... more Two-plated self-piercing eartags were first developed in the 19th century, but information on their retention rates is scarce. A method is presented that facilitates estimation of eartag retention rate by using a random sample of cows that initially had 2 tags (1 on each ear) placed for identification and at least 1 of which survived. Striving to adopt the European Union standard for cattle ear tagging, the Israeli veterinary service conducted a field test to evaluate the performance of plastic eartags under the conditions of a typical Israeli dairy farm. The initial sample (n=900 cows) was tagged on a single farm. Retention rates were estimated based on the ratio between the observed numbers of cows with 1 or 2 eartags in the surviving group (n=97 cows). Based on this long-term (>3 yr) field test, the highest yearly retention of flag eartags (0.89±0.03) was lower than expected (0.98). Tag design and on-farm management were key factors affecting tag retention. A better design of the feedline yoke system in the feeding area, avoiding slits that can entangle the eartags, would help increase tag retention.
Virology, 1981
ABSTRACT Interferon treatment, late in the SV40 lytic cycle, results in a block of viral protein ... more ABSTRACT Interferon treatment, late in the SV40 lytic cycle, results in a block of viral protein synthesis. Nevertheless, the quantity of the corresponding viral mRNAs is undiminished and the polyadenylation is normal. Under the same conditions, interferon treatment caused a three- to fivefold increase in internal methylation and a threefold increase in Cap II formation of SV40 mRNAs. Methylation of host mRNA and poly(A) minus RNA was also increased after interferon treatment, but only by a factor of 1–2. No dimethylated adenosines (m26A) were found in the overmethylated SV40 mRNAs and there was no change in the relative proportions of the various m6A sequences. Although the overmethylated SV40 mRNA was extracted from interferon-treated cells at a stage in which its in vivo translation was inhibited by 80%, it was translated in vitro as efficiently as normally methylated control mRNA.
MGG Molecular & General Genetics, 1983
The transfer systems of broad host range IncP plasmids are increasingly used in the genetic analy... more The transfer systems of broad host range IncP plasmids are increasingly used in the genetic analysis and manipulation of many gram-negative bacteria. We have examined the structural and functional relatedness of the transfer origins of ten different broad host range plasmids which belong to the IncP incompatibility group. The data reported here, together with our results on relatedness of the replication segments of these plasmids, demonstrate that the genomes of all IncP plasmids share extensive sequence homology in the regions specifying the transfer origin and replication functions. The homology results reveal the existence of two subclasses among IncP plasmids, designated here as IncPct and IncPfl. Furthermore, a functional analysis of the transfer origins of IncP plasmids suggests strongly that the DNA-nicking relaxation complex (Guiney and Helinski 1979) is required for plasmid transfer during conjugation.
Journal of Medical Genetics, 2005
Archiv für die gesamte Virusforschung, 1973
ABSTRACT Studies on temperature-sensitive events of four poliovirus ts mutants indicated that the... more ABSTRACT Studies on temperature-sensitive events of four poliovirus ts mutants indicated that the temperature-sensitive stage of ts2 and ts5 mutants occurs late in the reproduction cycle, but for ts 11 and tsM/23 it occurs both at early and at late stages of the cycle. RNA production by ts2, ts11 and tsM/23 mutants (RNA–) under nonpermissive conditions (40 C) is 13–14 per cent as compared with RNA production at 36 C. All the mutants under study form both 35S and 20S RNA under nonpermissive conditions, but the relative amount of 35S RNA synthesized at 40 C is considerably lower than at 36 C. A degradation of viral RNA under nonpermissive conditions is detected. Obtained data suggest that ts5 mutant (RNA+) under nonpermissive conditions is incapable of assembly of virus particles from synthesized components, but the multiplication of ts2, ts11 and tsM/23 mutants does not occur because of strong inhibition of RNA synthesis. Protein subvirion structures induced by ts5 mutant under nonpermissive conditions after subsequent transfer of the infected cells to permissive conditions, are incorporated into mature virus particles. Subvirion structures induced by ts M/23 mutant do not participate in further stages of morphogenesis after the infected cells are shifted to permissive conditions.
Archives of Virology, 1979
Monkey interferon (MKIF) produced in monkey BSC-1 cells infected with Newcastle disease virus sho... more Monkey interferon (MKIF) produced in monkey BSC-1 cells infected with Newcastle disease virus showed antiviral activity on human foreskin fibroblasts and RD114cells--a human line transformed by feline sarcoma virus. The titer of the monkey interferon in human cells was 10--30 fold greater than that found in several normal monkey (BSC-1, CV-1 or SV 40 transformed (C2, C6, T-22) monkey cell lines tested. Ten to fifteen-fold purification of MKIF without loss of activity could be achieved by chromatography on Phenyl-Sepharose CL-4B. Antiviral activity of MKIF was fully resistant to treatment with 1 per cent sodium dodecyl sulfate (SDS).
Archiv f�r die gesamte Virusforschung, 1973
Archiv f�r die gesamte Virusforschung, 1973
animal, 2010
Mitochondrial (mt) DNA D-loop heterogeneity, haplotype distribution and possible sub-population s... more Mitochondrial (mt) DNA D-loop heterogeneity, haplotype distribution and possible sub-population structures within the relevant populations are important for DNA-based traceability. To gain insight into this distribution, we compared 1515 Bos taurus mtDNA D-loop sequences available from GenBank to 219 sequences that we sequenced de novo. A pronounced ambiguous trace typical of C-track length heteroplasmy was encountered in 5% of the samples, which were excluded from the analysis. Previously undescribed mutations and haplotypes were observed in 6% and 63% of the sequences, respectively. B. taurus haplotypes divided into the taurus, indicus and grunniens types and 302 variable sites formed the 858 taurus haplotypes detected. Fifty-five sites displayed a complex level of variation. As each level represents an independent mutation event, a total of 399 mutations were traced, which could potentially explain independent formation of less than half (47%) of the haplotypes encountered: most haplotypes were derived from different combinations of these mutations. We suggest that a mutational hotspot may explain these results and discuss the usefulness of mtDNA for identity and maternity assurance.
Harefuah, 2006
RNA interference (RNAi), i.e. gene silencing, or gene expression down-regulation is the process w... more RNA interference (RNAi), i.e. gene silencing, or gene expression down-regulation is the process whereby a double-stranded RNA (dsRNA) induces the homology-dependent degradation of cognate messenger RNA (mRNA). When dsRNA is introduced into cells, an RNA-induced silencing complex (RISC) is assembled. RISC serves as cellular machinery that is responsible for the specific mRNA degradation. This process results in the subsequent reduction of the specific protein translated from appropriate mRNA. Short RNA duplexes (21 nucleotide), called small interfering RNA (siRNA), have become the major tool for induction of gene silencing. With the human genome mapped and sequenced, attempts are currently being made to manipulate the expression of genes involved in viral diseases, carcinogenesis and other disorders with the aim of developing novel therapies.
Human Mutation, 1997
The multiple endocrine neoplasia type 2 (MEN2) syndromes and Hirschsprung's disease (HSCR... more The multiple endocrine neoplasia type 2 (MEN2) syndromes and Hirschsprung's disease (HSCR) are inherited neurocristopathies characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, parathyroid disease, and gastrointestinal neuromatosis. Mutations in the RET proto-oncogene are the underlying cause of the MEN2 syndromes and some cases of HSCR. In this report, we show that Cys 618 Arg mutation cosegregates with familial MTC and HSCR in two Moroccan Jewish families in which no involvement of pheochromocytoma or parathyroidism was observed. A single haplotype shared by chromosomes bearing the Cys 618 Arg mutation in both families strongly suggests a founder effect for this mutation. We have observed in our and in several other previously reported families, an excess of maternal over paternal mutated RET alleles in offsprings affected by HSCR. We suggest that parental imprinting may play a role in the ethiology of HSCR caused by mutations in the RET protooncogene.
British Journal of Cancer, 2005
To gain insight into the molecular mechanisms involved in the inherited predisposition to melanom... more To gain insight into the molecular mechanisms involved in the inherited predisposition to melanoma and associated neural system tumours, 42 Jewish, mainly Ashkenazi, melanoma families with or without neural system tumours were genotyped for germline point mutations and genomic deletions at the CDKN2A/ARF and CDK4 loci. CDKN2A/ARF deletion detection was performed using D9S1748, an intragenic microsatellite marker. Allele dosage at the p14 ARF locus was analysed by quantitative real-time PCR employing a TaqMan probe that anneals specifically to exon 1b of the p14 ARF gene. For detecting point mutations, dHPLC and direct sequencing of the coding sequences of CDKN2A/ARF and CDK4 was used. No germline alterations in any of the tested genes were detected among the families under study. We conclude that in the majority of Ashkenazi Jewish families, the genes tested are unlikely to be implicated in the predisposition to melanoma and associated neural system tumours.
Journal of Virology
The synthesis of vaccinia virus-induced thymidine kinase is normally arrested several hours after... more The synthesis of vaccinia virus-induced thymidine kinase is normally arrested several hours after infection. In thymidine kinase-deficient LM cells infected with IHD strain of vaccinia virus, arrest occurs whether or not viral DNA synthesis is inhibited. With virus inactivated by UV irradiation, enzyme synthesis takes place, but arrest is abolished. It is suggested that an early viral genetic function is responsible for the cessation of thymidine kinase synthesis.
Israel journal of medical sciences
Journal of virology, 1972
Acetone added to the maintenance medium in a 1% concentration reduces the yield of infectious rab... more Acetone added to the maintenance medium in a 1% concentration reduces the yield of infectious rabbitpox virus in L-cell monolayer cultures by 90 to 97%. This concentration of the inhibitor is not toxic for cells. It was established that there is an inhibitor-sensitive stage late in the infectious cycle. Acetone exerted no significant influence on production of early viral messenger ribonucleic acid, formation of polyribosomes, deoxyribonucleic acid (DNA) replication, or protein synthesis. In the presence of acetone, the assembly of so-called "acetone particles" occurred. These particles are similar to normal virions by morphological and sedimentation properties but are slightly different from them in buoyant density. The amount of virus-specific DNA and the optical density of the "acetone particles" are the same as those of normal virions despite a 10- to 25-fold difference in the infectivity of the preparations.
Journal of virology, 1972
Five to seven minutes after addition of (14)C-amino acids to poliovirus-infected MiO cells, radio... more Five to seven minutes after addition of (14)C-amino acids to poliovirus-infected MiO cells, radioactivity is found only in 5S virus-specific structures. With increased time of labeling, radioactivity appears in considerable amounts also in the 14S area. In the presence of guanidine blocking the transition of 14S particles in subsequent structures in MiO cells, radioactivity is first detected in the 5S zone and then accumulates predominantly in 14S particles. These results indicate that formation of 5S particles and conversion of a part of their protein into 14S particles reflect the earliest stages of the morphogenesis of poliovirus. In contrast to poliovirus-infected HeLa cells, no 73S particles could be detected in MiO cells, nor could 73S structures be detected in poliovirus-infected MiO cells after a short incubation period (20 to 30 min) with radioactive amino acids, although formation of 150S virions was observed. Addition of guanidine to infected MiO cells leads to accumulati...
Journal of virology, 1971
Poliovirus-specific structures with sedimentation constants of 5, 14, 73, and 150S produced in in... more Poliovirus-specific structures with sedimentation constants of 5, 14, 73, and 150S produced in infected HeLa cells possess different antigenic specificities.
Journal of virology, 1970
Investigation of 15 poliovirus temperature-sensitive (ts) mutants by using physiological tests [f... more Investigation of 15 poliovirus temperature-sensitive (ts) mutants by using physiological tests [formation of virus-specific antigen and ribonucleic acid (RNA) under nonpermissive conditions] permitted us to divide them into three groups. From each group, one mutant was selected (ts 2, 5, 11), and a comparative study of poliovirus-related particle (5, 10, 73, and 150S) formation under permissive (36 C) and nonpermissive (40 C) conditions was carried out. The ts 2 and ts 11 are mutants with greatly reduced RNA synthesis which at 40 C produce particles with a sedimentation constant of 5S, and the ts 5 (RNA(+)) mutant produces both 5 and 10S particles. The relationship between different temperature-sensitive defects in the mutants is discussed. The results obtained indicate a possible role of 5S protein structures in morphogenesis of poliovirus.
Journal of Dairy Science, 2011
Two-plated self-piercing eartags were first developed in the 19th century, but information on the... more Two-plated self-piercing eartags were first developed in the 19th century, but information on their retention rates is scarce. A method is presented that facilitates estimation of eartag retention rate by using a random sample of cows that initially had 2 tags (1 on each ear) placed for identification and at least 1 of which survived. Striving to adopt the European Union standard for cattle ear tagging, the Israeli veterinary service conducted a field test to evaluate the performance of plastic eartags under the conditions of a typical Israeli dairy farm. The initial sample (n=900 cows) was tagged on a single farm. Retention rates were estimated based on the ratio between the observed numbers of cows with 1 or 2 eartags in the surviving group (n=97 cows). Based on this long-term (>3 yr) field test, the highest yearly retention of flag eartags (0.89±0.03) was lower than expected (0.98). Tag design and on-farm management were key factors affecting tag retention. A better design of the feedline yoke system in the feeding area, avoiding slits that can entangle the eartags, would help increase tag retention.
Virology, 1981
ABSTRACT Interferon treatment, late in the SV40 lytic cycle, results in a block of viral protein ... more ABSTRACT Interferon treatment, late in the SV40 lytic cycle, results in a block of viral protein synthesis. Nevertheless, the quantity of the corresponding viral mRNAs is undiminished and the polyadenylation is normal. Under the same conditions, interferon treatment caused a three- to fivefold increase in internal methylation and a threefold increase in Cap II formation of SV40 mRNAs. Methylation of host mRNA and poly(A) minus RNA was also increased after interferon treatment, but only by a factor of 1–2. No dimethylated adenosines (m26A) were found in the overmethylated SV40 mRNAs and there was no change in the relative proportions of the various m6A sequences. Although the overmethylated SV40 mRNA was extracted from interferon-treated cells at a stage in which its in vivo translation was inhibited by 80%, it was translated in vitro as efficiently as normally methylated control mRNA.
MGG Molecular & General Genetics, 1983
The transfer systems of broad host range IncP plasmids are increasingly used in the genetic analy... more The transfer systems of broad host range IncP plasmids are increasingly used in the genetic analysis and manipulation of many gram-negative bacteria. We have examined the structural and functional relatedness of the transfer origins of ten different broad host range plasmids which belong to the IncP incompatibility group. The data reported here, together with our results on relatedness of the replication segments of these plasmids, demonstrate that the genomes of all IncP plasmids share extensive sequence homology in the regions specifying the transfer origin and replication functions. The homology results reveal the existence of two subclasses among IncP plasmids, designated here as IncPct and IncPfl. Furthermore, a functional analysis of the transfer origins of IncP plasmids suggests strongly that the DNA-nicking relaxation complex (Guiney and Helinski 1979) is required for plasmid transfer during conjugation.
Journal of Medical Genetics, 2005
Archiv für die gesamte Virusforschung, 1973
ABSTRACT Studies on temperature-sensitive events of four poliovirus ts mutants indicated that the... more ABSTRACT Studies on temperature-sensitive events of four poliovirus ts mutants indicated that the temperature-sensitive stage of ts2 and ts5 mutants occurs late in the reproduction cycle, but for ts 11 and tsM/23 it occurs both at early and at late stages of the cycle. RNA production by ts2, ts11 and tsM/23 mutants (RNA–) under nonpermissive conditions (40 C) is 13–14 per cent as compared with RNA production at 36 C. All the mutants under study form both 35S and 20S RNA under nonpermissive conditions, but the relative amount of 35S RNA synthesized at 40 C is considerably lower than at 36 C. A degradation of viral RNA under nonpermissive conditions is detected. Obtained data suggest that ts5 mutant (RNA+) under nonpermissive conditions is incapable of assembly of virus particles from synthesized components, but the multiplication of ts2, ts11 and tsM/23 mutants does not occur because of strong inhibition of RNA synthesis. Protein subvirion structures induced by ts5 mutant under nonpermissive conditions after subsequent transfer of the infected cells to permissive conditions, are incorporated into mature virus particles. Subvirion structures induced by ts M/23 mutant do not participate in further stages of morphogenesis after the infected cells are shifted to permissive conditions.
Archives of Virology, 1979
Monkey interferon (MKIF) produced in monkey BSC-1 cells infected with Newcastle disease virus sho... more Monkey interferon (MKIF) produced in monkey BSC-1 cells infected with Newcastle disease virus showed antiviral activity on human foreskin fibroblasts and RD114cells--a human line transformed by feline sarcoma virus. The titer of the monkey interferon in human cells was 10--30 fold greater than that found in several normal monkey (BSC-1, CV-1 or SV 40 transformed (C2, C6, T-22) monkey cell lines tested. Ten to fifteen-fold purification of MKIF without loss of activity could be achieved by chromatography on Phenyl-Sepharose CL-4B. Antiviral activity of MKIF was fully resistant to treatment with 1 per cent sodium dodecyl sulfate (SDS).
Archiv f�r die gesamte Virusforschung, 1973
Archiv f�r die gesamte Virusforschung, 1973
animal, 2010
Mitochondrial (mt) DNA D-loop heterogeneity, haplotype distribution and possible sub-population s... more Mitochondrial (mt) DNA D-loop heterogeneity, haplotype distribution and possible sub-population structures within the relevant populations are important for DNA-based traceability. To gain insight into this distribution, we compared 1515 Bos taurus mtDNA D-loop sequences available from GenBank to 219 sequences that we sequenced de novo. A pronounced ambiguous trace typical of C-track length heteroplasmy was encountered in 5% of the samples, which were excluded from the analysis. Previously undescribed mutations and haplotypes were observed in 6% and 63% of the sequences, respectively. B. taurus haplotypes divided into the taurus, indicus and grunniens types and 302 variable sites formed the 858 taurus haplotypes detected. Fifty-five sites displayed a complex level of variation. As each level represents an independent mutation event, a total of 399 mutations were traced, which could potentially explain independent formation of less than half (47%) of the haplotypes encountered: most haplotypes were derived from different combinations of these mutations. We suggest that a mutational hotspot may explain these results and discuss the usefulness of mtDNA for identity and maternity assurance.
Harefuah, 2006
RNA interference (RNAi), i.e. gene silencing, or gene expression down-regulation is the process w... more RNA interference (RNAi), i.e. gene silencing, or gene expression down-regulation is the process whereby a double-stranded RNA (dsRNA) induces the homology-dependent degradation of cognate messenger RNA (mRNA). When dsRNA is introduced into cells, an RNA-induced silencing complex (RISC) is assembled. RISC serves as cellular machinery that is responsible for the specific mRNA degradation. This process results in the subsequent reduction of the specific protein translated from appropriate mRNA. Short RNA duplexes (21 nucleotide), called small interfering RNA (siRNA), have become the major tool for induction of gene silencing. With the human genome mapped and sequenced, attempts are currently being made to manipulate the expression of genes involved in viral diseases, carcinogenesis and other disorders with the aim of developing novel therapies.
Human Mutation, 1997
The multiple endocrine neoplasia type 2 (MEN2) syndromes and Hirschsprung's disease (HSCR... more The multiple endocrine neoplasia type 2 (MEN2) syndromes and Hirschsprung's disease (HSCR) are inherited neurocristopathies characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, parathyroid disease, and gastrointestinal neuromatosis. Mutations in the RET proto-oncogene are the underlying cause of the MEN2 syndromes and some cases of HSCR. In this report, we show that Cys 618 Arg mutation cosegregates with familial MTC and HSCR in two Moroccan Jewish families in which no involvement of pheochromocytoma or parathyroidism was observed. A single haplotype shared by chromosomes bearing the Cys 618 Arg mutation in both families strongly suggests a founder effect for this mutation. We have observed in our and in several other previously reported families, an excess of maternal over paternal mutated RET alleles in offsprings affected by HSCR. We suggest that parental imprinting may play a role in the ethiology of HSCR caused by mutations in the RET protooncogene.
British Journal of Cancer, 2005
To gain insight into the molecular mechanisms involved in the inherited predisposition to melanom... more To gain insight into the molecular mechanisms involved in the inherited predisposition to melanoma and associated neural system tumours, 42 Jewish, mainly Ashkenazi, melanoma families with or without neural system tumours were genotyped for germline point mutations and genomic deletions at the CDKN2A/ARF and CDK4 loci. CDKN2A/ARF deletion detection was performed using D9S1748, an intragenic microsatellite marker. Allele dosage at the p14 ARF locus was analysed by quantitative real-time PCR employing a TaqMan probe that anneals specifically to exon 1b of the p14 ARF gene. For detecting point mutations, dHPLC and direct sequencing of the coding sequences of CDKN2A/ARF and CDK4 was used. No germline alterations in any of the tested genes were detected among the families under study. We conclude that in the majority of Ashkenazi Jewish families, the genes tested are unlikely to be implicated in the predisposition to melanoma and associated neural system tumours.