Saving Carrie (Book 1 in the HPO1 series)

Neil Stenton

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Renatus 2 by John A. Sep 05, Neil Stenton made a comment on their review of Renatus 2. You don't need to read Renatus befo I thoroughly enjoyed Renatus and coudn't wait to start on Renatus 2, it didn't disappoint and is a great follow up. You don't need to read Renatus before this, but I would if I were or you'd be missing out on the start of a great series. I'd call it a classic British police procedural with elements of whodunnit, 2 to 3 storylines and a hint of paranormal.

If you've read Renatus you'll know what I mean. In fact if you have then you should be reading Renatus 2 now! Saunders puts just enough description to the scenes to make them believable, making it a fast paced read and real page turner. He makes you care about the characters, want the best for them, and worry about them when they face problems - and that's a winner as far as I'm concerned. I said in my review of Renatus that it would make a great TV police drama, and this would be a great episode 2.

Suffice to say that I'm ready for Renatus 3 now. Sep 03, Neil Stenton started reading. Perfect Pawn by Andrew G. Manhattan North by John Mackie. Renatus by John A. Feb 16, Neil Stenton wants to read. Search for a book to add a reference. We take abuse seriously in our discussion boards. Only flag comments that clearly need our attention. The distribution of basal-body couplets at the anterior ends of ciliary rows, along with the underlying apical filamentous band 68 , was modified in a consistent manner within such a reversed region 53 , Nonetheless, the internal organization of the ciliary rows remained normal in every other respect 53 , 76 , and the ultrastructure of the basal bodies and associated cytoskeletal elements of the OA 68 , 69 was completely normal.

The primary OA pOA of janus cells sometimes expressed modest abnormalities 53 , , whereas the sOA was usually highly abnormal. In general, OAs that developed within globally reversed domains whatever the origin of these domains were variable structural compromises engendered by a conflict between the normal intrinsic handedness of the basal bodies and the pervasive influence of the reversed global left-right polarity 39 , These two influences typically ended up specifying opposite directions of alignment of basal-body couplets into promembranelles, often eventually resulting either in a compromise inverted oral structures or in chaos fragmented structures.

The frequent absence of a second set of oral structures in janus cells could be partially accounted for by a failure of sOAs to develop to completion as a consequence of having to respond to conflicting patterning instructions; because a normal or nearly normal pOA was present on the opposite surface, these cells could feed, survive, and grow. The question then arises: Two lines of evidence suggest that it does.

First, a detailed analysis of the placement of the CVP sets revealed that i the midpoint of the two CVP sets was halfway between the two sets of oral structures when both were present and ii the positions of these CVP sets were the same irrespective of whether a sOA was present or not In wild-type cells, the pmf marked the oral meridian and was not found elsewhere. In janA-1 and janC-2 cells, the pmf was commonly also present along the mid-dorsal axis, even when secondary oral structures were not present there Originally, the phenotypes resulting from mutations at all of the janus loci were deemed nearly identical, except that high penetrance of the secondary oral structures in janA mutants depended on the presence of a separate janA -specific enhancer.

However, two differences between janA and janC mutant clones were discovered more recently 22 , One was the mysterious failure of the apical band of janA-1 but not of janC-2 cells to be immunostained with 12G9 or anti-centrin antibodies The other was the inability of janA but not janB or janC mutant stocks to complete conjugation when mated with each other This blockage may supply a useful means for selecting revertants in attempts to clone the JANA gene by complementation, with the hope that reversal of the conjugation block will simultaneously reverse the cortical anomaly.

Although the janus mutants often have two sets of oral structures Fig. Thus, janus mutant cells are not true doublet cells; rather, they are singlet cells in which a broad domain has undergone a reversal of circumferential polarity. Photos and diagrams contrasting janus and doublet-former cells. The two OAs are identical, not mirror images as they superficially appear to be in this photograph, since the membranelles of the OA on the viewer's right are seen from the opposite cell surface underneath the lightly stained ribbed wall. Single macronuclei Mac are indistinctly visible in both the janusA-1 and the dbf1 - 1 cell.

Interestingly, our mutant hunt did turn up a true Siamese-twin doublet-forming mutation Fig. These were perfectly normal Siamese-twin doublets with twofold rotational symmetry, like the doublets studied by Nanney et al. The modal ciliary row number of doublets was 28, which was near the lower limit of the expected row number for doublet cells; this fit with the observation that doublet cells tend to lose rows rapidly shortly after their formation but maintain the doublet condition until the number of ciliary rows falls into the range of 25 to 28 rows , The only unusual aspect of the dbf1 - 1 doublet clones was that they were selected as recessive homozygotes following mutagenesis.

The analysis of double mutants is especially useful for working out metabolic or developmental pathways, in which epistasis can sometimes allow one to infer the order of successive steps. However, when we employed this method with our structural mutations, we typically found joint expression of phenotypes, notably in our analysis of cells bearing mutations of different fission arrest genes Double-mutant analysis was carried out for janus mutations combined with a variety of other mutations.

The phenotype of double homozygotes of janA-1 and disA-1 was, unsurprisingly, totally additive: The severe local-global polarity incompatibility in globally reversed domains seems to have interfered with the formation of large pseudomacrostome-type secondary oral structures. Double homozygotes of mutations at all three janu s loci were made with bcd1 - 1 and were thoroughly analyzed The details were complex, but three relatively straightforward observations were made. Second, two significant aspects of mutual enhancement were found in all three jan-bcd combinations: In these cases, the bcd1 mutation appeared to be influencing the expression of the janus phenotype.

Third, an opposite influence was found only in the janB-1 - bcd1 - 1 combination: Our fairly extensive analysis of the janC-1 - hpo1 - 1 combination remains unpublished. The main finding was, again, that there is phenotypic additivity. Yet a priori, there are two different ways in which a jan - hpo cell might express such additivity: The latter was observed, so that one can speak of the janus phenotype being superimposed on a hypoangular body plan, rather than the reverse.

In addition, the slippage that took place during every successive episode of oral development in hypoangular cells also occurred in the janC-1 - hpo2 - 1 double homozygote. Slippage was directed toward the right for the primary oral meridian as in hypoangular mutants alone and occasionally toward the left for the secondary oral meridian. Just how this could prevent the two oral meridians from ultimately joining and possibly annihilating each other is not clear at the moment.

One outcome of the analyses of both the jan - bcd and jan - hpo double homozygotes is that the simple notion of some fixed dorsal domain that is uniquely subject to a global reversal as shown in Fig. It appears as if mutations at any of three janus loci may create the essential preconditions for a reversal, whereas the genetic background in which these mutations are expressed would influence the locations at which these reversals may be expressed.

These locations might even be dynamic within a mutant clone. Finally, double homozygotes of bcd1 - 1 and hpo1 - 1 were constructed specifically to test whether the reduction in the number of ciliary rows bearing CVPs that is characteristic of the hpo mutants would also be exhibited in a genetic background of bcd-1 , which by itself increases the number of CVP rows. Since the phenotypes of the two mutants are opposites, one-way epistasis might have been an outcome, but the actual result was a compromise: My thesis here, which is not particularly novel 10 , is that genic control and structural inheritance should be thought of as complementary rather than antagonistic.

Genic mutations can generate phenotypes that then are structurally inherited; they can attenuate the transmission of preexisting structural phenotypes; and in a few cases, they may bring about major topological transitions previously known only from studies of nongenic cortical inheritance. The classic structurally inherited phenotype is the ciliary-row inversion in Paramecium see Fig.

However, ciliary-row inversions, which then are propagated cytotactically, are also generated by cortical disturbances brought about by the kin 80 and crochu 77 mutations. Another possible example of the mutational generation of phenotypes that subsequently are structurally inherited is the doublet-former dbf1 - 1 mutation in T. This mutation resulted in the appearance of perfect doublets similar to those generated by the failure of conjugants to separate. Variations in the frequency of occurrence of this initiating event would account for the highly variable penetrance of this mutation, since doublets, once formed, propagate their condition for a while but tend to revert to singlets by loss of ciliary rows and possibly also become diluted by overgrowth by singlets in a mixed culture Two specific cases in which genic mutations attenuate cytotactic propagation are the single-gene-controlled basal-body-deficient bbd condition in Euplotes minuta 34 and the low kinety number lkn1 - 1 mutant in Tetrahymena , described above.

In both, the fidelity of propagation of ciliary rows, which is normally high 34 , , is seriously compromised.

This condition is probably due to two factors: These imperfections in no way contradict the general rule of spatially accurate structural guidance within ciliary rows but instead point out its likely dependence on the normally invariant propagation of new ciliary units anterior to old ones within ciliary rows 2 , 26 , The recently achieved capacity for molecular modification of crucial cytoskeletal components of basal bodies has, in some cases, led to relaxation of these structural constraints. As examples, an RNA interference-induced depletion of the basal-body centrin in Paramecium and certain modifications of gamma-tubulin in Tetrahymena have both brought about the formation of new basal bodies at abnormal locations outside of the longitudinal axis of existing ciliary rows.

Since the fidelity of propagation of ciliary units within ciliary rows is likely to depend on the intrinsic polarity of basal bodies 11 , I would expect that such modifications would attenuate the fidelity of cytotaxis. Genic mutations that strengthen cytotactic propagation would be hard to select, given the already very high fidelity of longitudinal perpetuation of ciliary rows in wild-type P. However, whereas cytotactic propagation of ciliary-row inversions and associated structural modifications exists in Tetrahymena , it is not as strong as it is in Paramecium 97 , One could perhaps imagine genically specified molecular alterations that might strengthen cytotactic propagation in the former organism.

Finally, the janus mutations can be thought of as inducing expression of the widespread ciliate capacity to generate and propagate nongenic reversals in the global arrangement of cortical structures. Whereas in the dorsoventrally flattened spirotrich ciliates, such as Stylonychia or Oxytricha , this capacity is most strongly expressed in the propagation of stable mirror image doublets Fig. This transitory mirror image doublet stage is geometrically remarkably similar to the phenotype of the janus mutant The fact that this configuration can be observed in genetically wild-type cells indicates that the janus mutations did not manufacture the pattern reversals but rather created conditions under which Tetrahymena cells were stimulated to express their normal capacity to generate such a reversal.

This perhaps accounts for the surprising frequency of janus mutations, which have appeared in breedable form on seven different occasions at three widely separated gene loci, despite our inefficient means for selecting such mutations. If and when they are cloned and sequenced, I suspect that these janus genes will be found to encode widely differing molecules, the absence of any one of which could serve as a trigger to unleash a latent topological capability.

Author Updates

It is impossible to predict accurately which of the 27 mutant-genes whose phenotypic effects have been briefly described in this review will turn out to be the most interesting once they are cloned by complementation. I would nonetheless like to conclude this review by developing an argument for a special interest in three of them. One obvious rule is that there is equatorial partitioning along the anteroposterior axis prior to division constriction.

I have described above mutations in several genes that modify or even ignore that rule; the cloning and sequencing of these genes might lead to insights into the molecular basis of that partitioning. But here I would like to emphasize a more subtle empirical rule, which has held up remarkably well. This is the rule of relational CVP positioning around the cell circumference, discovered long ago by David Nanney With certain refinements and complications, Tetrahymena cells position their CVP midpoint at just under one-quarter of the cell circumference to the right or clockwise of the oral meridian Fig.

In Siamese-twin doublets, CVPs are positioned just under one-quarter of the distance between the two oral meridians Fig.

Saving Carrie

These rules, which in my view must reflect some fundamental global positional order around the cell circumference, are well obeyed in most mutants and nongenic variants, so much so that they have been little remarked upon in this review. Reversed singlet cells seem to flout the rules by placing their CVP sets to the left rather than the right of the oral meridian, but when one does the relevant counts, one finds that these cells still obey Nanney's rules perfectly, only making their measurements in the opposite direction The global dimensions in reversed and normal cells are as similar as our left and right hands this does not apply to the OAs of the reversed cells, because they have unreversed basal bodies to contend with.

Even janus cells do their utmost to obey Nanney's rules, taking into account the existence of side-by-side normal and reversed cortical domains in the same cell 42 , In my view, the most interesting mutants are those that violate these rules. The reasoning is this: When such genes are mutated, the rules are likely to be altered. Which of the mutations that I have described can cause cells to flout Nanney's rules? I can immediately identify three. The first is broadened cortical domains bcd1 , which shifts the CVP set somewhat to the right and, above all, dramatically broadens the CVP field width.

The second is the enigmatic II8G clone, which broadens the CVP field angle and also causes a major shift of the CVP set to the right; it is not clear whether this strain can still produce viable progeny. Finally, there are the hypoangular hpo1 mutations. They have been selected four times independently, are all allelic, and always produce the same phenotype, suggesting that unlike janus they are affecting a unique gene product that happens to specify a portion of the cell's positional rulebook.

These mutants break just about every rule in the book, most notably by reducing the CVP distance variably depending on the degree of expression. So, possibly, the HPO1 gene encodes an indispensable part of the rule-setting machinery. I have limited time and resources available for distributing mutant stocks directly, though I will respond to requests by prioritizing shipments to the Tetrahymena Stock Center if the stocks are not there already! I feel no proprietary interest in any of the mutations selected in my laboratory and will be delighted if any or all of the responsible genes are cloned and sequenced by interested researchers.

I will also be happy to share unpublished information about these mutations to the extent that it is available. Since it is doubtful that any of these mutants have commercial value, it is desirable that any interesting results obtained from the study of these mutations be published in the open literature, although it should be apparent from perusal of this review that the author himself has not always obeyed this injunction.

I would like first to express my gratitude and appreciation for all those who participated in the selection and analysis of the mutations that originated in my laboratory. This includes above all my long-term associates: Jenkins, who laboriously isolated and genetically analyzed virtually all of these mutations, and E. Marlo Nelsen, who did much of the phenotypic analysis of both genic mutants and nongenic cortical variants.

I also wish to specially acknowledge the contribution of F. Paul Doerder, who in taught us the essential genetic procedures and isolated our first mutations, and that of Maria Jerka-Dziadosz, who returned to Iowa repeatedly from her home base at the Nencki Institute in Warsaw and efficiently analyzed the phenotypes of some of our most interesting mutants. My two graduate students during this period, Timothy Lansing and Eric Cole, each made one of the mutations his own, and both enriched the laboratory with their personal perspectives.

I am also grateful for the continuous presence and support of my long-time colleague, Norman E. Williams, who was already working on ciliate morphogenesis at the University of Iowa when I arrived in , and who in first encouraged me to overcome my timidity and submit a grant application to search for cortical mutants in Tetrahymena. Anne Frankel made a major contribution in helping to analyze the temperature-sensitive periods of three mutants and has continually given me indispensable support and assistance, in part by supplying me with detailed and uninhibited editorial advice for every publication that I have written since , including this one.

The remaining errors and infelicities are solely my own responsibility. National Center for Biotechnology Information , U. Journal List Eukaryot Cell v. Published online Jul Author information Copyright and License information Disclaimer. This article has been cited by other articles in PMC. Open in a separate window. Genes and structural patterns in ciliates. Gene designations are as follows: Mutations affecting the organization of basal bodies in the ciliary rows. Mutations affecting the development of the OA.

Mutations affecting subdivision along the anteroposterior axis. Mutations affecting organization along the circumferential axis.

Acknowledgments I would like first to express my gratitude and appreciation for all those who participated in the selection and analysis of the mutations that originated in my laboratory. Fine structure, reconstruction, and possible functions of components of the cortex of Tetrahymena pyriformis. The morphogenesis of basal bodies and accessory structures of the cortex of the ciliated protozoan Tetrahymena pyriformis. Membrane recycling at the cytoproct in Tetrahymena. Genetics of Tetrahymena , p. Proposed genetic nomenclature rules for Tetrahymena thermophila , Paramecium primaurelia , and Paramecium tetraurelia.

Mitochondrial associations with specific microtubular components of the cortex of Tetrahymena thermophila. Response of the mitochondrial pattern to changes in the microtubule pattern. Development of the ciliary pattern of the oral apparatus of Tetrahymena thermophila. Regulation of the pattern of basal bodies within the oral apparatus of Tetrahymena thermophila. The role of the cytoplasm in heredity.

Polarities of the centriolar structure: Cytoplasmic inheritance of the organization of the cell cortex of Paramecium aurelia. Mirror-image doublets of Tetmemena pustulata: Studies on the macronuclei of doublet Paramecium tetraurelia: Tetrahymena thermophila , p. Oral morphogenesis during transformation from microstome to macrostome and macrostome to microstome in Tetrahymena vorax strain V 2 , type S. Integration of oral structures in the cdaA1 mutant of Tetrahymena thermophila.

Okadaic acid promotes cell division in synchronized Tetrahymena pyriformis and in the cell division-arrested cdaA1 temperature-sensitive mutant of T. Protrusion formation in the cell-division arrested mutant Tetrahymena thermophila cdaA1 , and the elucidation of some rules governing cytoskeletal growth. The DNA replication schedule is not affected in a division-blocked mutant of Tetrahymena thermophila.

Conjugal blocks in Tetrahymena pattern mutants and their cytoplasmic rescue. Biochemical and cytological evidence for an overabundance of mucocysts in the bcd pattern mutant of Tetrahymena thermophila. Interactions between the janus and bcd cortical pattern mutants in Tetrahymena thermophila: The development of basal bodies in Paramecium. Form and pattern in ciliated protozoa: Defective spatial control in patterning of microtubular structures in mutants of the ciliate Paraurostyla.

Morphogenesis in multi-left-marginal mutant.

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Macronuclear genome sequence of the ciliate Tetrahymena thermophila , a model eukaryote. A long stringent sequence signal for programmed chromosome breakage in Tetrahymena thermophila. Participation of the undulating membrane in the formation of the oral replacement primordium of Tetrahymena pyriformis. A genically determined abnormality in the number and arrangement of basal bodies in a ciliate. An analysis of cell-surface patterning in Tetrahymena. Propagation of cortical differences in Tetrahymena. What are the developmental underpinnings of evolutionary changes in protozoan morphology?

The patterning of ciliates. Cell biology of Tetrahymena thermophila. Cell polarity in ciliates, p. Discontinuities and overlaps in patterning within single cells.

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How the mirror-image pattern specified by a janus mutation of Tetrahymena comes to expression. Intracellular pattern reversal in Tetrahymena thermophila. Transient expression of a janus phenocopy in balanced doublets. Positional reorganization in compound janus cells of Tetrahymena thermophila. The effects of supraoptimal temperatures on population growth and cortical patterning in Tetrahymena pyriformis and Tetrahymena thermophila. A mutant of Tetrahymena thermophila with a partial mirror-image duplication of cell surface pattern.

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Nature of genic control. Development of the ciliature of Tetrahymena thermophila. Spatial subdivision prior to cytokinesis. Mutations affecting cell division in Tetrahymena pyriformis , syngen 1. Phenotypes of single and double homozygotes. Intracellular pattern reversal in Tetrahymena thermophila: Mutational analysis of patterning of oral structures in Tetrahymena. A graded basis for the individuality of intracellular structural arrays. Temperature-sensitive periods of mutations affecting cell division in Tetrahymena thermophila.

Selective mirror-image reversal of ciliary patterns in Tetrahymena thermophila homozygous for a janus mutation. Causal relations among cell cycle processes in Tetrahymena pyriformis: Selection and genetic analysis. Mutational analysis of patterning of oral structures of Tetrahymena. Effects of increased size on organization. Molecular cloning of the gene for p85 that regulates the initiation of cytokinesis in Tetrahymena.

Inheritance of cortical patterns in ciliated protozoa, p. Macmillan, New York, NY. Cytogeometrical determination of ciliary pattern formation in the hypotrich ciliate Stylonychia mytilus. Stability and field regulation. Patterning and assembly of ciliature are independent processes in hypotrich ciliates.

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The cloning by complementation of the pawn-A gene in Paramecium. Genic control of cortical pattern in Euplotes. Structural inheritance in Paramecium: Cytoskeleton-related structures in Tetrahymena thermophila: Patterning of ciliary structures in janus mutant of Tetrahymena with mirror-image cortical duplications.

The origin of mirror-image symmetry doublet cells in the hypotrich ciliate Paraurostyla weissei. Mirror-image configuration in the cortical pattern causes modifications in propagation of microtubular structures in the hypotrich ciliate Paraurostyla weissei.

Spatial coordinates in a double-recessive mutant. Transmission of a genetic trait through total conjugation in a holotrich ciliate Paraurostyla weissei. Genetic basis of the multi-left-marginal mutant. Cell shape, growth rate, and cortical pattern aberrations in an abnormal strain of the hypotrich ciliate Paraurostyla weissei. Genetic approaches to ciliate pattern formation: Analysis of the phenotype. Uncoupling of basal body duplication and cell division in crochu , a mutant of Paramecium hypersensitive to nocodazole.

The dynamics of filamentous structures in the apical band, oral crescent, fission line and the postoral meridional filament in Tetrahymena thermophila revealed by monoclonal antibody 12G9. Cellular polarity in ciliates: Garreau de Loubresse, and J. Development of surface pattern during division in Paramecium.

Defective spatial control in the mutant kin Syndrome of the failure to turn off mitotic activity in Tetrahymena thermophila: Temperature-sensitive mutations affecting cortical morphogenesis and cell division in Paramecium tetraurelia. How to write a great review. The review must be at least 50 characters long. The title should be at least 4 characters long.

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Chi ama i libri sceglie Kobo e inMondadori. Sniper by Neil Stenton. Buy the eBook Price: Available in Russia Shop from Russia to buy this item. Or, get it for Kobo Super Points! Ratings and Reviews 0 1 star ratings 0 reviews. How to write a great review Do Say what you liked best and least Describe the author's style Explain the rating you gave Don't Use rude and profane language Include any personal information Mention spoilers or the book's price Recap the plot. Close Report a review At Kobo, we try to ensure that published reviews do not contain rude or profane language, spoilers, or any of our reviewer's personal information.

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