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PubMed1997

Molecular evolution of multiply-antibiotic-resistant staphylococci.

Methicillin-resistant Staphylococcus aureus (MRSA) is an intractable nosocomial pathogen. The chemotherapeutic intransigence of this organism stems from its predilection to antimicrobial resistance as a consequential response to selective pressures prevailing in the clinical environment. MRSA isolates are frequently resistant to all practicable antimicrobials except the glycopeptide, vancomycin. Although antimicrobial resistance sometimes arises via chromosomal mutation, the emergence of multiply-antibiotic-resistant staphylococci is primarily due to the acquisition of pre-existent resistance genes; such determinants can be encoded chromosomally or by plasmids and are often associated with transposons or insertion sequences. Clinical staphylococci commonly carry one or more plasmids, ranging from small replicons that are phenotypically cryptic or contain only a single resistance gene, to larger episomes that possess several such determinants and sometimes additionally encode systems that mediate their own conjugative transmission and the mobilization of other plasmids. The detection of closely related plasmids, elements and/or genes in other hosts, including coagulase-negative staphylococci and enterococci, attests to interspecific and intergeneric genetic exchange facilitated by mobile genetic elements and DNA transfer mechanisms. The extended genetic reservoir accessible to staphylococci afforded by such horizontal gene flux is fundamental to the acquisition, maintenance and dissemination of staphylococcal antimicrobial resistance in general, and multiresistance in particular.

Drug Resistance, Microbial↗
PubMed2006

Incongruent plastid and nuclear DNA phylogenies reveal ancient intergeneric hybridization in Pilosella hawkweeds (Hieracium, Cichorieae, Asteraceae).

Phylogenetic relationships for Hieracium subgen. Pilosella were inferred from chloroplast (trnT-trnL, matK) and nuclear (ITS) sequence data. Chloroplast markers revealed the existence of two divergent haplotype groups within the subgenus that did not correspond to presumed relationships. Furthermore, chloroplast haplotypes of the genera Hispidella and Andryala nested each within one of these groups. In contrast, ITS data were generally in accord with morphology and other evidence and were therefore assumed to reflect the true phylogeny. They revealed a sister relationship between Pilosella and Hispidella and a joint clade of Hieracium subgenera Hieracium and Chionoracium (Stenotheca) while genus Andryala represented a third major lineage of the final ingroup cluster. Detailed analysis of trnT-trnL character state evolution along the ITS tree suggested two intergeneric hybridization events between ancestral lineages that resulted in cytoplasmic transfer (from Hieracium/Chionoracium to Pilosella, and from the introgressed Pilosella lineage to Andryala). These chloroplast capture events, the first of which involved a now extinct haplotype, are the most likely explanation for the observed incongruencies between plastid and nuclear DNA markers.

Asteraceae↗
PubMed1985

[Variants of the plasmid pAS8 delta with increased frequency of integration into Rhodopseudomonas sphaeroides chromosome--the result of IS8-element duplication].

The possible participation of IS8 and IS elements of Rhodopseudomonas sphaeroides in cointegrate formation by chromosome of the purple bacterium and plasmid pAS8-121 delta has been studied. The plasmid derivatives having deleted Tn7 have been studied. Plasmid integration into the chromosome of the purple bacterium is shown to be mediated by IS8 element of the plasmid. Plasmid derivatives having the integration potential increased for two orders were isolated by a series of intergeneric conjugational crosses during which plasmid pAS8-121 delta was transferred from Rhodopseudomonas sphaeroides (cointegrate of plasmid and chromosome) to Escherichia coli (plasmid in an autonomous state) and back to Rhodopseudomonas sphaeroides. The restriction analysis of plasmid DNA digested by Hpal and Smal restriction endonucleases has revealed the tandem duplications of IS8 in plasmids capable of integration into the chromosome of the purple bacterium with a high frequency.

Chromosomes, Bacterial↗
PubMed1988

Escherichia coli Spheroplast-Mediated Transfer of pBR322 Carrying the Cloned Ruminococcus albus Cellulase Gene into Anaerobic Mutant Strain FEM29 by Protoplast Fusion.

Intergeneric protoplast fusion between Escherichia coli HB101 with pBR322 carrying the cloned o-(carboxymethyl)cellulase (CMCase) gene of Ruminococcus albus (Pro Leu Ap Km) and an anaerobic mutant strain, FEM29 (Trp His Ap Km), with dehydrodivanillin-degrading activity was performed in the presence of 40% polyvinyl alcohol 300 under aerobic and anaerobic conditions to transfer the cloned cellulase gene into the mutant. The mutant FEM29 had a unique property. When it was incubated in liquid medium with 1% glucose and sucrose, protoplasts could be produced autogenously and regenerated on the agar slant. E. coli spheroplasts formed from a plasmid-amplified overnight culture after 10 min of treatment with lysozyme (20 mug/ml) in a hypertonic solution (0.01 M Tris hydrochloride [pH 7.5], 0.4 M mannitol). Protoplast regeneration rates of FEM29 and HB101 were 30 and 83%, respectively, on the agar-yeast extract medium. Ap Km fusants were obtained at high frequency: 1.7 x 10 anaerobically and 8.2 x 10 aerobically. These fusants showed 23 to 57% of CMCase and dehydrodivanillin-degrading activities, respectively, as compared with parental strains. All the fusants isolated were gram-negative rods with main phenotypes such as urease and catalase activities as in HB101 and esterase and chymotrypsin activities as in FEM29. Southern hybridization experiments suggested that pBR322 with the cloned CMCase gene existed autonomously in the fusant cells. This is the first report describing transfer of pBR322 with a cloned cellulase gene into an anaerobic mutant by polyvinyl alcohol-mediated fusion with an E. coli spheroplast.

Journal Article↗
PubMed1991

Intergeneric somatic hybridization in Gramineae: somatic hybrid plants between tall fescue (Festuca arundinacea Schreb.) and Italian ryegrass (Lolium multiflorum Lam.).

Tall fescue (Festuca arundinacea Schreb.) protoplasts, inactivated by iodoacetamide, and non-morphogenic Italian ryegrass (Lolium multiflorum Lam.) protoplasts, both derived from suspension cultures, were electrofused and putative somatic hybrid plants were recovered. Two different genotypic fusion combinations were carried out and several green plants were regenerated in one of them. With respect to plant habitus, leaf and inflorescence morphology, the regenerants had phenotypes intermediate between those of the parents. Southern hybridization analysis using a rice ribosomal DNA probe revealed that the regenerants contained both tall fescue- and Italian ryegrass-specific-DNA fragments. A cloned Italian ryegrass-specific interspersed DNA probe hybridized to total genomic DNA from Italian ryegrass and from the green regenerated somatic hybrid plants but not to tall fescue. Chromosome counts and zymograms of leaf esterases suggested nuclear genome instability of the somatic hybrid plants analyzed. Four mitochondrial probes and one chloroplast DNA probe were used in Southern hybridization experiments to analyze the organellar composition of the somatic hybrids obtained. The somatic hybrid plants analyzed showed tall fescue, additive or novel mtDNA patterns when hybridized with different mitochondrial gene-specific probes, while corresponding analysis using a chloroplast gene-specific probe revealed in all cases the tall fescue hybridization profile. Independently regenerated F. arundinacea (+) L. multiflorum somatic hybrid plants were successfully transferred to soil and grown to maturity, representing the first flowering intergeneric somatic hybrids recovered in Gramineae.

Cells, Cultured↗
PubMed2007

Nucleolar remodeling in nuclear transfer embryos.

Transcription of the ribosomal RNA (rRNA) genes occurs in the nucleolus and results in ribosome biogenesis. The rRNA gene activation and the associated nucleolus formation may be used as a marker for the activation of the embryonic genome in mammalian embryos and, thus serve to evaluate the developmental potential of embryos originating from varied nuclear transfer protocols. In bovine in vivo developed embryos, functional ribosome-synthesizing nucleoli become structurally distinct toward the end of the 4th post-fertilization cell cycle. In embryonic cell nuclear transfer embryos, fully developed nucleoli are not apparent until the 5th cell cycle, whereas in somatic cell nuclear transfer embryos the functional nucleoli emerge already during the 3rd cell cycle. Intergeneric reconstructed embryos produced by the fusion of bovine differentiated somatic cell to a nonactivated ovine cytoplast fail to develop fully functional nucleoli. In bovine in vivo developed embryos, a range of important nucleolar proteins (e.g., topoisomerase I, upstream binding factor and RNA polymerase I, fibrillarin, nucleophosmin and nucleolin) become localized to the nucleolar anlage over several cell cycles. This relocation is completed toward the end of the 4th cell cycle. A substantial proportion of bovine embryos produced by nuclear transfer of embryonic or somatic cells to bovine ooplasts display aberrations in protein localization in one or more blastomers. This information is indicative of underlying aberrations in genomic reprogramming and may help to explain the abnormalities observed in a proportion of fetuses and offspring derive from nuclear transfer embryos.

Animals↗
PubMed1981

Intraspecific and intergeneric mobilization of non-conjugative resistance plasmids by a 24.5 megadalton conjugative plasmid of Neisseria gonorrhoeae.

pLE2451, a 24.5 megadalton conjugative plasmid from Neisseria gonorrhoeae, was capable of efficiently mobilizing gonococcal beta-lactamase plasmids between gonococci and from gonococci to Haemophilus influenzae and restriction-deficient Escherichia coli. Donor strains of N. gonorrhoeae carrying pLE2451 were also found to be capable of mobilizing a variety of non-conjugative plasmids originally derived from enteric bacteria or Haemophilus species when such plasmids were resident in E. coli. Nevertheless, pLE2451 was not detected physically in E. coli or H. influenzae transconjugants. This suggests that the plasmid is unstable in these hosts but survives transiently to provide transfer functions for mobilization. The proficiency of pLE2451 in promoting intraspecific and intergeneric mobilization was not paralleled by pUB701, pRI234 and pFR16017, a series of conjugative plasmids derived originally from Haemophilus species. These plasmids were incapable of mobilizing even Haemophilus beta-lactamase plasmids, such as RSF0885, between Haemophilus species.

Conjugation, Genetic↗
PubMed2000

Duties to future generations, proxy consent, intra- and intergenerational equity: the case of nuclear waste.

How does one deal with problems of risk transfer if it is the case that increasing risks to future generations decreases the risks to present generations, and increasing the risks to present generations decreases the risks to future generations? In the case of high-level nuclear waste and spent fuel, for example, should billions of dollars be spent to secure the wastes and protect future generations, or should the same monies be spent on present-day needs, under the assumption that future generations will be better able to deal with the waste than we are at present? Although these questions may appear insoluble, they become less so when one recognizes several common ethical and logical errors that beset many discussions of technological risk and duties to future generations. After briefly explaining the grounds for inter- and intragenerational equity, this analysis argues for three propositions about many treatments of inter- and intragenerational ethics: (1) these discussions often err because they frame policy arguments in terms that ignore rights and focus on maximizing welfare or utility, (2) they err because they frequently frame policy arguments in ways that set inter- and intragenerational welfare at odds, when they are not, because they ignore ameliorating practices and the conditions for proxy consent, and (3) they also err because they engage in risk practices that do not match their risk rhetoric.

Journal Article↗
PubMed2004

Sex ratios in mule duck embryos at various stages of incubation.

Mule duck hatcheries have long reported varying degrees of unbalance in the sex ratio, with a preponderance of male mules at hatching. The aim of the present study was to assess the distributions of sex ratios at various stages of development in embryos originating from intra- and intergeneric crosses between parental lineages (Muscovy male x Muscovy female, Pekin male x Pekin female, Muscovy male x Pekin female or Mule, and Pekin male x Muscovy female or Hinny). In Experiment I, embryo sexing was performed on Days 1 and 5 of incubation (by multiplex PCR) and at hatching (by vent observation). The sex ratio was not significantly modified during the early stages of embryo development whatever the genetic origin (P>0.05, Days 1 and Day 5) but our results in mule and hinny ducklings confirmed the preponderance of males among normally hatched ducklings originating from the intergeneric lineage (58.9 and 55.4% males in mules and hinnies, respectively; P<0.05 in both cases). Sex ratio (vent sexing) in second grade (cull) ducklings revealed that 68% of these ducklings were females (P<0.05). In Experiment II, the distribution of sex ratio was also performed in mule duck eggs from 6 batches (400,000 eggs/batch) first examined for fertility (candling) on Day 18 of incubation. These results indicate that the percentage of males present in the population of normally hatched ducklings increases when fertility decreases. In addition, this experiment also revealed that 83.7-90.5% of viable male mule embryos develop up to hatching, compared to only 43.0-51.0% of female mule embryos. Given that a deviation in sex ratio during the first stages of incubation is unlikely (Experiment I), it is concluded that the skewed sex ratio of mule ducks at hatching is primarily due to increased late mortality in female mule embryos occurring between egg transfer and hatching. This mortality originated, at least in part, from the intergeneric origin of female mules, and was marked to a greater or lesser extent depending on the initial success of fertilization in a given batch, a possible indication that the initial quality of gametes may selectively exert its influence at the later stages of embryo development.

Animals↗
PubMed1985

Merodiploidy in Escherichia coli-Salmonella typhimurium crosses: the role of unequal recombination between ribosomal RNA genes.

Previous workers have shown that intergeneric crosses between Salmonella typhimurium and Escherichia coli produce a high proportion of merodiploid recombinants among the viable progeny. We have examined the unequal cross-over event that was responsible for a number of intergeneric merodiploids. The merodiploids that we studied were all heterozygous for the metB-argH interval and were the products of intergeneric conjugal crosses. We found that when the S. typhimurium donor had its transfer origin closely linked to metB and argH, all recombinants examined were merodiploid, and they generally arose as F-prime factors. Many of these F-prime factors had been created by recombination between flanking rrn genes in the donor. When the S. typhimurium Hfr transfer origin was more distant from the selected markers, quite different results were obtained. Depending on the donor, 19-47% of the recombinants that acquired the donor argH+ or metB+ genes were merodiploid for these loci, but none of the recombinants were F-prime. A majority of the merodiploids had a novel (nonparental) rrn gene, indicating that unequal recombination between nonidentical rrn genes was a prevalent mechanism for establishing the merodiploidy. Both tandem and nontandem duplications were found. Some of the merodiploids duplicated E. coli genes in addition to acquiring S. typhimurium genes. Some merodiploids contained the oriC region from each parent. Of a total of 118 intergeneric merodiploids characterized from all donors, 48 different genotypes were observed, and 38 of the 48 had one or more nonparental rrn operons.

Crosses, Genetic↗
PubMed2002

Lateral and vertical intergenerational exchange in rural Malawi.

Contemporary empirical literature on family resource flows in developing countries focuses on vertical flows between parents and children. Using data from the 1999 Family Transfers Project in Malawi this article examines a broader set of flows between adult respondents and their surviving parents, and paternal and maternal aunts and uncles. It compares the frequency and value of material and monetary flows, and the frequency of provision of other services, among these relatives. It also explores variation on these parameters across three ethnic groups, each of which has discrete normative patterns of descent, inheritance and postmarital residential arrangements. Results suggest that: (i) intergenerational support networks in Malawi are both vertical and lateral; (ii) in their transfer relationships, working aged adults have a net loss to parents, but a net gain to uncles and aunts, implying the existence of an institutionalized network for the transfer of resources among branches of the family; and (iii) lineal structures privilege kin of certain gender for certain roles. Maternal and paternal aunts are the largest source of material transfers among the matrilineal Yao, and paternal and maternal uncles are the largest source among the patrilineal Tumbuka.

Journal Article↗
PubMed1995

[Demographic variables and social dependency: annual and intergenerational comparisons].

"Drawing on a profile of age-specific expenditures for selected [Canadian] Government programmes (services and transfers), we examine the effect of demographic changes and labour force participation on social expenditures in the upcoming decades. In terms of cross-sectional analysis, increased activity rates and particularly a postponed retirement age would exercise a major impact.... Using a different approach, it is possible to distinguish for each generation the social benefits received and corresponding contributions. Whereas the amount of benefits received by a specific cohort essentially depends on its size, contributions vary according to annual social expenditures. The demographic structures are such that the generations born before 1991 will profit from an excess in benefits...while for the following generations the situation will be reversed.... For all scenarios with negative population growth, future generations may expect to incur a deficit in terms of social expenses." (SUMMARY IN ENG AND SPA)

Age Factors↗
PubMed1995

Intergenerational work as an adjunct to psychoanalysis and psychotherapy.

Psychotherapy and psychoanalysis are opportunities for individuals to repair faulty aspects of their development that have resulted in symptoms or other difficulties in living. Although transference is the major therapeutic tool in this work, it is not the only one. The potential resources for healing that exist in family relationships is great, especially as these relationships go on long after therapy has ended. We are all living longer; families of three and four generations are no longer uncommon. There are many adult patients who have one or both parents alive and well. Intergenerational work can be a useful adjunct where there is no severe narcissistic pathology or psychosis in either patient or parent. It is especially helpful in cases where there is severe resistance and insight is not effective in promoting change. "By focusing constantly on the patient's transference distortions and ignoring reality elements we undermine self-esteem and make him feel he is always wrong, sick or crazy" (Greenson, 1978b,p. 434). The addition of intergenerational work in the course of psychoanalysis/psychotherapy can shorten the time of therapy and be another tool for dealing with resistance. This work has theoretical implications for the modification of the place that transference has in psychoanalytic therapy. By placing greater emphasis on the patient's real relationships in influencing intrapsychic change we pave the way to exciting clinical and theoretical possibilities.

Adult↗
PubMed2006

From risky behavior to health risk: continuity across two generations.

The purpose of this study was to determine the impact of childhood aggression and social withdrawal on adolescent health risk behaviors and adult health outcomes, and to examine the transfer of health risk to preschool offspring. This was a prospective, longitudinal, and intergenerational study of 114 mothers from disadvantaged neighborhoods, who were identified in childhood as being highly aggressive and/or withdrawn or with low scores on these 2 behavioral risk dimensions, and their preschool offspring aged 1 to 6 years old. The health histories of mothers (adolescent health risk behavior, health during pregnancy, current symptoms) and target children were taken during structured interviews conducted at home. Regression analyses tested the relationship between maternal childhood risk status and subsequent health outcomes, and these were followed by structural equation modeling of a proposed intergenerational pathway. Maternal childhood aggression predicted current health risk behaviors (e.g., daily cigarette smoking), whereas maternal childhood social withdrawal was not associated with maternal health risk at the time of testing. Mothers who had high scores on both aggression and withdrawal were more likely to engage in adolescent health risk behavior, which was directly related to health problems in preschoolers (even after controlling for covariates, such as neonatal health status and sex). In summary, there are distinct health trajectories for women who are highly aggressive and socially withdrawn in childhood, with implications for women's long-term health. Specifically, aggression in girls is likely to lead to health risk behaviors that may also place the next generation at risk for pediatric illness. Results are interpreted in terms of the health-hostility link, best known in adult men and intergenerational models.

Adolescent↗
PubMed1997

An urban intergenerational program for cancer control education.

BACKGROUND: Recognizing the disparities in cancer morbidity and mortality that exist between African Americans and whites, an urban university and its neighborhood community undertook the development of an education program to transfer state-of-the-art cancer prevention, detection, and treatment information from an academic medical center to community residents, including school-age children. METHODS: An intergenerational, multilevel intervention was developed to: 1) assess the health beliefs of the community, 2) identify, develop, and train an intergenerational group of community residents who would serve as health educators, and 3) promote behavioral change among the target population. RESULTS: Ten community residents were trained as educators. Over the course of two years they conducted cancer education programs that reached 775 adults. During the same period, the school-based educational intervention reached 264 seventh-grade students. CONCLUSIONS: Implications for the design and implementation of community-based cancer education programs in this African American community are identified.

Academic Medical Centers↗
PubMed1998

Corynebacterium striatum chloramphenicol resistance transposon Tn5564: genetic organization and transposition in Corynebacterium glutamicum.

The clinical isolate Corynebacterium striatum M82B (formerly Corynebacterium xerosis M82B) carries the 50-kb R-plasmid pTP10 conferring resistance to the antibiotics chloramphenicol, erythromycin, kanamycin, and tetracycline. DNA sequence analysis of the chloramphenicol resistance region revealed the presence of the 4155-bp transposable element Tn5564. The ends of Tn5564 are identical 22-bp inverted repeats flanked by a 6-bp target site duplication. The central region of Tn5564 encodes the chloramphenicol resistance gene cmx, specifying a transmembrane chloramphenicol efflux protein, and an open reading frame homologous to transposases of insertion sequences identified in Arthrobacter nicotinovorans and Bordetella pertussis. Furthermore, the 1715-bp insertion sequence IS1513 encoding a putative transposase of the IS30 family is an integral part of Tn5564 and is located upstream of cmx. For transposon mutagenesis, Tn5564 was transferred to Corynebacterium glutamicum on a mobilizable Escherichia coli plasmid using RP4-mediated intergeneric conjugation. Transposition of Tn5564 in C. glutamicum occurred with a frequency of 3.3 x 10(-8) and resulted in an insertion into target sites containing the central palindromic tetranucleotide CTAG. A Tn5564-induced mutant strain of C. glutamicum was found to carry the transposon in the ftsZ gene region.

Amino Acid Sequence↗
PubMed2001

[Effect of the gene for bacterial hemoglobin vhb on the effectiveness of the process of Escherichia coli-Streptomyces interspecies conjugation and production of antibiotics in streptomycetes].

The bacterial hemoglobin vhb gene was cloned from sliding bacterium Vitreoscilla sp. as an element of the system ensuring survival of this microorganism in an environment that contains insufficient amount of oxygen. The vhb gene was transferred from Escherichia coli to some Streptomyces strains, producers of antibiotics, by the method of intergeneric conjugation using conjugative-integrative plasmid vectors pIH1 and pCH2. The stability of plasmid DNA inheritance was analyzed in the genomes of exconjugants. A positive effect of the vhb gene on processes of conjugation and antibiotic production in a number of examined strains was shown.

Anti-Bacterial Agents↗
PubMed1989

Intergeneric conjugation between Escherichia coli and Streptomyces species.

We have constructed Escherichia coli-Streptomyces shuttle plasmids which are capable of conjugal transfer from E. coli to Streptomyces spp. These plasmids contained the pBR322 and pIJ101 origins of replication and the RK2 (IncP) origin of transfer. The transfer of plasmid was specifically dependent the presence of a 760-base-pair, cis-acting, oriT-containing fragment and on RP4 (IncP) functions supplied in trans. Conditions of mating and selection of exconjugants were analyzed with Streptomyces lividans as recipient. Plasmid transfer to other Streptomyces species was also demonstrated.

Conjugation, Genetic↗