Transmission Of Genetic Material Research Articles

Guest editorial: Interventional radiology in India - The road ahead

Interventional radiology (IR) is the ‘medical specialty devoted to advancing patient care through the innovative integration of clinical and imaging-based diagnosis and minimally invasive therapy.’[1] Over the years, there has been a gradual and steady growth in this exciting radiology subspecialty in India. In the seventies and eighties, IR practice was limited to hospitals in New Delhi, Mumbai, Trivandrum, and Lucknow, but over the years there has been an expansion in the practice of IR in India as a whole. When one looks back at IR's steady growth in India, it is clear that this is not merely an outcome of the growth of diagnostic radiology practices but is due to a combination of factors, which include increasing demands from referring physicians, the widespread availability of imaging equipment for guided procedures, IR's potential to serve as a convenient alternative to open surgical procedures and reduce recovery time, and the tremendous advances in IR hardware. Today, IR is an integral part of various clinical procedures, finding a role in vascular diseases, oncology, stroke management, women's health, pediatrics, and back pain. Available to us in India are a variety of new IR techniques that have been successfully incorporated into clinical practice, which involve the use of catheters, guide wires, glide wires, balloons for angioplasty, coils, liquid embolizing agents, stents and stent grafts, radiofrequency ablation devices, thrombectomy devices, etc. Let us briefly look at the leading causes of death worldwide. In high-income countries the list includes heart disease, stroke, lung cancer, colon and rectum cancers, breast cancer, and stomach cancer. In low- and middle-income countries, in addition to the above, the common causes include HIV/AIDS, perinatal conditions, tuberculosis, and road traffic accidents.[2] The clinical management of these varied entities places a burden on society and drains the exchequer. As interventional radiologists, we should encourage the timely and judicious use of IR techniques in the prevention and cure of diseases. When we look at the future of IR in India, there are two challenges that merit scrutiny and deliberation. The first is the need for vigorous efforts for the motivation of students and radiology residents in all the leading Indian medical institutions so that we can create a second rung of specialists who can gradually step into the shoes of the current practitioners, as is happening in many other countries.[3] The second challenge is clinical gene therapy. This rapidly developing and promising therapeutic modality is knocking on our doors. Gene therapy involves ‘transferring recombinant genetic material (DNA/ RNA) into the host cell in order to change the gene expression in the host cell to gain a therapeutic effect.’[4] Interventional radiologists will ‘play an important role in the transmission of genetic materials to the target cells,’[5] using percutaneous injection or catheter systems. In the times ahead, interventional radiologists will play an increasingly important role in selecting, guiding, and monitoring clinical gene therapy.[6] Research in gene therapy applications is underway in diverse areas, including infections, malignancies, metabolic disorders, and enzyme deficiencies. Besides these, the treatment of ischemia of the myocardium and extremities with angiogenetic growth factors to promote collateral artery development is being evaluated. Similarly, the role of gene therapy in treating stenoses following balloon angioplasty or stenting and in therapeutic angiogenesis are also being evaluated.[5] It is therefore important that interventional radiologists be prepared, continuously updating their knowledge to keep abreast of the advances in molecular imaging and clinical gene therapy applications and issues.[7] The interventional radiologist must know it all: from the awareness of gene therapy terminology to concepts in cloning, vectors, and detection of their expression; from a functional knowledge of molecular imaging and immunology, to understanding the different types of catheters used in the practice of gene transfer technology, such as pressure diffusion, passive diffusion, and mechanical and electrically strengthened catheters.[5] Interventional radiologists should also recognize and be aware of the ongoing advances in the development of novel treatment technologies, commonly used targeted tracers and probes, and of the visualization tools employed to analyze targeted therapy. The time is not far, when catheter-based delivery of tagged stem cells to target lesions becomes an established procedure. Indeed the situation experienced by practicing interventional radiologists today has been correctly summed up by Brian Stainken: IR “… appeals to people who have a creative streak, people who like procedural care, people who like to use their hands, people who want to make a difference.”[1] There are exciting times ahead on the IR road with brightly shining milestones along the way. For those interested in participating in IR academic activities, the Indian Society of Vascular and Interventional Radiology (ISVIR) is a useful professional forum. Its website is http://www.isvir.in/

Evidence of multiple horizontal transfers of the long terminal repeat retrotransposon RIRE1 within the genus Oryza

Horizontal gene transfer, defined as the transmission of genetic material between reproductively isolated species, has been considered for a long time to be a rare phenomenon. Most well-documented cases of horizontal gene transfer have been described in prokaryotes or in animals and they often involve transposable elements. The most abundant class of transposable elements in plant genomes are the long terminal repeat (LTR) retrotransposons. Because of their propensity to increase their copy number while active, LTR retrotransposons can have a significant impact on genomics changes during evolution. In a previous study, we showed that in the wild rice species Oryza australiensis, 60% of the genome is composed of only three families of LTR retrotransposons named RIRE1, Wallabi and Kangourou. In the present study, using both in silico and experimental approaches, we show that one of these three families, RIRE1, has been transferred horizontally between O. australiensis and seven other reproductively isolated Oryza species. This constitutes a new case of horizontal transfer in plants.

Stan biologiczny populacji ludzkich a przemiany środowiska społeczno-ekonomicznego

Adaptation of life to the environment occurs at two levels - that of an individual and that of a population. In the first step of the process of adaptation variability is produced. It provides necessary material for the second step - selection. Variability is generated during the phylogeny, from one generation to the next. However, variability can also be generated during individual ontogeny at least by protective mechanisms of instinctive behaviors of animals and conscious cultural human actions. Variability originates from point mutations and chromosomal aberrations occurring during transmission of genetic material from generation to generation and through activation, or deactivation, of genes that alters their expression. This variability determines phenotypic differences among individuals. Variability thus produced is subjected to selection because how a phenotype is formed determines its ability to survive and to produce offspring. In human populations, adaptation occurs via biological and via cultural processes. Humans with their culture - especially medicine and social care - protect lives of individuals who otherwise would have been eliminated by natural selection.Hereditary differences among various geographic groups of modern people occur with low frequency - just a fraction of a percentage point. From observations of phenotypes it can be concluded that both structural alterations in the DNA and differences in gene expression cause variations, the majority of genes are inactive at various stages of ontogeny, while various portions of the genotype become active at different times in the life of an individual.Environment influences variation in three ways: (1) by causing mutations or by altering gene expression and (2) by providing conditions for the formation of a phenotype coded by a particular genotype and (3) as a factor of selection, including occurrence of cultural behaviors modifying effects of natural selection. It seems that the main aim of future research in human ecology should be search for the answer to following questions: 1. Can gene expression be changed during ontogeny? 2. To what extent such changes can be inherited? 3. To what extent is there an increase in the occurrence of genes that do not allow survival without special care (genetic load), and 4. How will all this influence future of our species?

Identification of DNA-PK in the arthropods: Evidence for the ancient ancestry of vertebrate non-homologous end-joining

Cellular life depends upon the preservation and transmission of genetic material. Double stranded DNA breaks (DSBs) cause catastrophic gene loss in cell division and must be promptly and accurately repaired. In eukaryotes DSBs may be repaired by either non-homologous end-joining (NHEJ), single strand annealing or homologous recombination (HR). Vertebrate NHEJ has been shown to depend upon the DNA-dependent protein kinase (DNA-PK) consisting of the phosphatidylinositol 3 (PI 3)-kinase like (PIKK) catalytic sub-unit (DNA-PKcs) and the DNA targeting factor Ku. Our analysis of recently completed genomes found several novel PIKKs in Anopheles gambiae and Drosophila melanogaster including a novel mosquito DNA-PKcs orthologue, the first non-vertebrate DNA-PKcs described to date. We also detected a DNA-PKcs fragment in the high quality EST set of Apis mellifera ligustica (honey bee) suggesting that DNA-PK is a far older and more important eukaryotic complex than previously thought.

HF2: a double-stranded DNA tailed haloarchaeal virus with a mosaic genome.

HF2 is a haloarchaeal virus infecting two Halorubrum species (Family Halobacteriaceae). It is lytic, has a head-and-tail morphology and belongs to the Myoviridae (contractile tails). The linear double-stranded DNA genome was sequenced and found to be 77 670 bp in length, with a mol% G+C of 55.8. A total of 121 likely open reading frames (ORFs) were identified, of which 37 overlapped at start and stop codons. The predicted proteins were usually acidic (average pI of 4.8), and less than about 12% of them had homologues in the sequence databases. Four complete tRNA-like sequences (tRNA-Arg, -Asx, -Pro and -Tyr) and an incomplete tRNA-Thr were detected. A transcription map showed that most of the genome was transcribed and that the synthesis of transcripts occurred in a highly organized and reproducible pattern over a 5 h infection cycle. Transcripts often spanned multiple ORFs, suggesting that viral genes were organized into operons. The predicted ORF and observed transcript directions matched well and showed that transcription is mainly directed inwards from the genome termini, meeting at about 45-48 kb, and this was also a turning point in a cumulative GC-skew plot. The low point in cumulative GC-skew, near the left end, was a region rich in short repeats and lacking ORFs, which is likely to be an origin of replication. The HF2 genome is a mosaic of components from widely different sources, demonstrating clearly that viruses of haloarchaea, like their bacteriophage counterparts, are vectors for the exchange and transmission of genetic material between wide taxonomic distances, even across domains.

Telomere length, telomere-binding proteins, and DNA damage signaling.

The transmission of genetic material is fundamental toall living organisms. It has been recognized since thework of McClintock and Muller in the 1930s that a broken eukaryotic chromosome end is unstable and can leadto genomic rearrangements. This work defined naturalends, or telomeres, as special structures that provide stability to chromosome ends (McClintock 1938; Muller1938)...

MAP kinases in pollen.

The male gametophyte of flowering plants has a highly regulated developmental programme to ensure efficient fertilization of the ovule and the faithful transmission of genetic material to the offspring. Cell cycle control mechanisms dictate the formation of the vegetative and generative (sperm) cells, while an increase in transcriptional/translational activity and the accumulation of stored proteins and mRNA is followed by a quiescent state at maturation. A switch to a new developmental programme occurs after the pollen tube lands on the stigma with the formation of the pollen tube, growth through the style, and subsequent fertilization. Apart from the internal control mechanisms involved in this developmental programme, pollen grains must cope with physical changes during development within the anther (desiccation) and subsequently during germination on the stigma (rehydration). The metabolic and structural changes that occur throughout these processes should require signaling mechanisms to co-ordinate the appropriate response, and recent data demonstrate the presence in pollen of an array of molecules belonging to diverse signalling pathways, including mitogen-activated protein (MAP) kinases. The role of MAP kinases in pollen is discussed in the context of the various developmental and physical changes that occur throughout pollen maturation and germination.

Mistakes & Molecular Evolution

T HIS article examines the role of mistakes in molecular evolution of bacteria. A summary of the main points in this manuscript is provided in Table 1. Interacting physical, chemical and biological factors cause changes (mutations, deletions, insertions, recombination) in DNA (and its replication) that have a significant role in prokaryotic evolution, as it is unlikely that genetic information was transmitted over long periods of time without changes (some being mistakes) in the copying process (replication). The ability of bacterial genomes to remain relatively constant while changing genome size (Riley 1989) and gene orders provides a means for the evolution of bacteria (Trevors 1995). Information cannot be transmitted over extended periods of time without some mistakes being introduced into the copying process; in this case, genetic material (Reanney 1984). Mistakes provide a mechanism for genetic change or deterioration/improvement of the genetic material. External factors that affect long-term transmission of genetic material (almost always DNA) are present in the biosphere. These include radiation, fluctuating temperatures, changing nutrient status of the system, and the presence of mutagenic chemicals. Given these interacting physical, chemical and biological factors, it is not unreasonable that mistakes in DNA (and its replication) had a significant role in molecular evolution. As stated by Reanney (1984), the frequency of errors in DNA replication in eukaryotic organisms is one incorrect nucleotide for every 109 to 1011 bases during replication. However, as pointed out by Reanney (1984), the present situation is likely to be different from replication of primitive genetic material which could have exhibited an error of replication frequency of 10-1 to 10-2 per base per generation. This means that during evolution, the frequency of mistakes decreased as the replication mechanisms evolved into the present systems in bacteria and other organisms. This refinement in the replication (copier) systems was necessary if organisms were to maintain genome sizes and gene orders within a range while at the same time provid-

Genetic relationships in Lens species and parentage determination of their interspecific hybrids using RAPD markers

Broadening of the genetic base and systematic exploitation of heterosis in cultivated lentils requires reliable information on genetic diversity in the germplasm. The ability of random amplified polymorphic DNA (RAPD) to distinguish among different taxa of Lens was evaluated for several geographically dispersed accessions/cultivars of four diploid Lens species. This study was carried out to assess whether RAPD data can provide additional evidence about the origin of the cultivated lentil and to measure genetic variability in lentil germplasm. Three cultivars of Lens culinaris ssp. culinaris, including one microsperma, and two macrosperma types, and four wild species (L. culinaris ssp. orientalis, L. odemensis and L. nigricans) were evaluated for genetic variability using a set of 1 11-mer and 14 random 10-mer primers. One hundred and fifty-eight reproducible and scorable DNA bands were observed from these primers. Genetic distances between each of the accessions were calculated from simple matching coefficients. Split decomposition analysis of the RAPD data allowed construction of an unrooted tree. This study revealed that (1) the level of intraspecific genetic variation in cultivated lentils is narrower than that in some wild species. (2) L. culinaris ssp. orientalis is the most likely candidate as a progenitor of the cultivated species, (3) L. nigricans accession W6 3222 (unknown) and L. c. ssp. orientalis W6 3244 (Turkey) can be reclassified as species of L. odemensis and (4) transmission of genetic material in Lens interspecific hybrids is genotypically specific, as identified by the RAPD markers in our study.

The Origin of Intracellular and Intercellular Pathogens

I propose that the very earliest cell could not have contained intracellular parasites in the sense of independent, self-benefiting agents that were detrimental to their host. Before there were effective ways to extract energy by methanogenesis and photosynthesis, the world ecosystem, I have argued, was very sparse and essentially monophyletic (Koch, 1994). During much or all of this time, nontransmissible agents, comparable to plasmids, would have been selected against as long as they could not synchronize their growth with that of their single-celled host. Even when such an adaptation was initiated, it must have been one that was likely crude and imperfect, and frequently failed. The transmission of genetic material via subcellular vectors would have depended on the later development of special mechanism for the introduction of nucleic acids into living cells. only after living forms became abundant could and efficient and effective transmissible intracellular pathogen prosper, because by then a trnsmissible agent could be destructive to its host and more successfully to a new host. The implication is that much of the earliest evolution of either the host's cellular functions or the parasite's techniques and strategies proceeded without gene transfer. Support for these ideas is presented, starting from hypotheses concerning the nature of the first life forms and leading to a scenario for the development of transmissible intracellular pathogens.

The selfobject as immortal self

This paper begins by defining the selfobject and elucidating its role in the structuring of the self for each unique individual. The self becomes a repository of the memory images of emotional experiences with significant others. This process of internalization through which the self is continually nourished, and which enables it to grow, goes on throughout life. However, as a case example illustrates, the ability to internalize a selfobject depends on the ability to receive and to give love. Once the selfobject is incorporated into the self of "an other" it is perpetuated in another, is perpetuated, analogous to the transmission of genetic material. Each individual carries others within himself or herself and has the potentiality for continuing to live within the self of another. This is a kind of immortality.

Mechanisms of spontaneous mutagenesis: clues from mutational specificity.

Spontaneous mutation can be viewed as the sum total of everything that can go wrong with DNA during the life cycle of a cell. Yet, the student of mutation only sees a small fraction of the events; only those changes that produce a selectable and hence observable alteration in phenotype. Moreover, our observations are made through a filter; the majority of errors made by a cell are corrected by the plethora of mechanisms that have evolved to maintain the accurate transmission of genetic material. Our increasing knowledge about mechanisms of DNA repair and their influence on mutation, in combination with the newly developed ability to clone and sequence mutants, provide an opportunity to explore the sources of spontaneous mutation.

Differentiation — A consequence of idiotype-environment interaction

The present paper deals with a model of idiotype-environment interaction and its application to a tissue culture experiment with birch ( Betula pendula ROTH.). The data of the experiment are characterized with respect to the physiological reactions and are discussed in the light of the model. The main results of the paper are: With respect to the environmental action one has to discriminate between the environment inside and outside the cell (external and internal environment). The environmental influences cause a differential gene activity which lead to transient differentiation states and to final states of differentiatedness. During mitosis two types of information transmission take place: transmission of genetic material (the “blue-print”) and transmission of the milieu (the “experience” of previous events). They together give rise to differentiation. The data of the experiment show that differentiation is no one-way street: Because of the transmitted milieu it is sometimes easier to regain an earlier differentiation state than to reach a new one. Only the interaction of idiotype (sum of genetic information) and the milieu state (internal environment) causes parallel as well as divergent development of cell lines. The model is also used to reinterpret some selected papers in the literature.

トマトの接木による果皮及び果肉色変異

Induction of hereditary changes by grafting in tomato was reconfirmed by combination of the cultivar Jubilee (yellow skin-orange flesh) as scion and the cultivar Tiny Tim (yellow skin-red flesh) as stock.The phenotypic change from yellow-orange (Jubilee type) to yellow-red (Tiny Tim type) was observed in the grafted scion (G0) on the Tiny Tim stock. In the selfed progeny (G1) from this Tiny Tim type variant fruit on the Jubilee scion, new type (colorless-red) was segregated in addition to Jubilee type (yellow-orange) and Tiny Tim type (yellow-red). The genotypic change of skin and flesh color is assumed to have occurred from Yyrr (yellow-orange) to YyRr (yellow-red) in the grafted scion and in the first self ed progeny, Y-R-(yellow-red), Y-rr (yellow-orange) and yyR-(colorless-red) were segregated from the YyRr variant (G0). Most of the successive progenies (G2 and G3) obtained from the segregants in the G1 generation accorded with Mendelian inheritance. But the phenotypic changes inexplicable in terms of Mendelism were assumed to have changed from yyR-(G1) to Y-R-(G2), from Y-rr (G2) to Y-R-(G3) and from yyR-(G2) to Y-R-(G3). But yyrr (colorless-orange) was not detected in all successive progenies. No other characters than skin and flesh color have been changed in the present study.It is likely to suppose that the transmission of genetic material from stock to scion would have occurred, though the mechanism is quite obscure yet.