bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recombinant human lecithin-cholesterol acyltransferase in patients with atherosclerosis: phase 2a primary results and phase 2b design
Authors: Bonaca Marc P , George Richard T , Morrow David A , Bergmark Brian A , Park Jeong-Gun , Abuhatzira Liron , Vavere Andrea L , Karathanasis Sotirios K , Jin ChaoYu , She Dewei , Hirshberg Boaz , Hsia Judy , Sabatine Marc S 
Published: January 2021

AbstractAimsReverse cholesterol transport (RCT) removes cholesterol and stabilizes vulnerable plaques. In addition, high-density lipoprotein (HDL) may be cardioprotective in acute myocardial infarction (MI). Lecithin-cholesterol acyltransferase (LCAT) may enhance RCT. The objective of this study was to investigate the pharmacokinetics, pharmacodynamics, and safety of multiple ascending doses of recombinant human LCAT (MEDI6012) to inform a Phase 2b programme.Methods and resultsThis was a randomized, blinded, placebo-controlled, dose-escalation Phase 2a study of MEDI6012. Patients were randomized into one of four cohorts (40, 120, 300 mg IV weekly ×3 doses, or 300 mg IV-push, 150 mg at 48 h and 100 mg at 7 days). All cohorts were planned to randomize 6:2 (MEDI6012 vs. placebo). The primary endpoints were baseline-adjusted area under the curve (AUC) from 0 to 96 h post dose 3 (AUC 0–96 h) for HDL-C, HDL cholesteryl ester (HDL-CE), and total cholesteryl ester (CE). The primary safety endpoints were treatment-emergent adverse events. A total of 32 patients were randomized. MEDI6012 significantly increased AUC 0–96 h for HDL-C, HDL-CE and CE in a graded fashion with increasing doses. Relative to placebo, MEDI6012 increased HDL-C at Day 19 by 66% (95% CI 33–99, P = 0.014) with 120 mg and 144% (95% CI 108–181, P &lt; 0.001) with 300 mg. An IV-push increased HDL-C by 40.8% at 30 min. Overall adverse events were similar between groups with no severe, life-threatening/fatal adverse events, or neutralizing antibodies.ConclusionsMultiple ascending doses of MEDI6012 were safe and well tolerated and significantly increased HDL-C, HDL-CE and CE in a dose-related manner. These data support the ongoing Phase 2b programme investigating MEDI6012 in ST-elevation MI.
HAPLOID SELECTION FOR LOW TEMPERATURE TOLERANCE OF TOMATO POLLEN
Authors: Zamir Daniel , Tanksley Steven D , Jones Richard A 
Published: January 2021

ABSTRACT
Pollen grains were harvested from an interspecific F1 hybrid between the cultivated tomato, Lycopersicon esculentum Mill., and its wild relative Lycopersicon hirsutum Humb. & Bonpl., a low temperature tolerant accession originating from an altitude of 3200 m in the Peruvian Andes. The two species differ for electrophoretically-detectable loci that mark six (possibly seven) of the 12 tomato chromosomes. Isozyme analysis of the BC1 populations derived from controlled pollinations at normal and low temperatures indicates a significant skewing of allelic frequencies favoring two independent chromosome segments of L. hirsutum at low temperatures. The results demonstrate that gametophytic selection for low temperature tolerance of tomato pollen is determined, at least in part, by genes expressed in the haploid pollen.
MEIOTIC DIPLOID PROGENY AND MEIOTIC NONDISJUNCTION IN SACCHAROMYCES CEREVISIAE
Authors: Sora Silvio , Lucchini Giovanna , Magni Giovanni E 
Published: January 2021

ABSTRACT
Abnormalities in chromosome number that occurred during meiosis were evaluated with a specially-constructed diploid strain of Saccharomyces cerevisiae. The strain is heterozygous for six markers of the right arm of chromosome V and heterozygous for cyh2 (resistance to cycloheximide) on chromosome VII.—Selection of meiotic spores on a medium containing cycloheximide and required nutrilites—except those for the markers of the right arm of chromosome V—allows the growth of aberrant clones belonging only to two classes: a) diploid clones, caused by failure of the second meiotic division, with a frequency of 0.54 × 10-4 per viable spore; and b) diplo V, aneuploids derived from nondisjunctions in meiosis I or meiosis II, with a total spontaneous frequency of 0.95 × 10-4 per viable spore. About two-thirds of the aneuploids originated during meiosis I, the rest during meiosis II. An investigation of these events in control meioses and after treatment with MMS, Benomyl and Amphotericin B suggests that this assay system is suitable for screening environmental mutagens for their effects on meiotic segregation.
GENETIC ANALYSES OF ENDOTHIA PARASITICA: LINKAGE DATA FOR FOUR SINGLE GENES AND THREE VEGETATIVE COMPATIBILITY TYPES
Authors: Anagnostakis Sandra L 
Published: January 2021

ABSTRACT
The loci cre, met and ts segregate independently in Endothia parasitica. The phenotype brown (br) seems to be determined by an allele at or very near the cre locus. The vegetative compatibility types (v-c) 5 and 39 are determined by different alleles at a locus that is not linked to cre, met or ts. Analysis of two crosses of v-c 5 strains by v-c 10 strains provides evidence that these two v-c groups are different at 5 or more v-c loci.
INTERACTIONS OF ZESTE MUTATIONS WITH LOCI EXHIBITING TRANSVECTION EFFECTS IN DROSOPHILA MELANOGASTER
Authors: Gelbart William M , Wu Chao-Ting 
Published: January 2021

ABSTRACT
Zeste (1-1.0; 3A3) mutations have been known to modify the expression of two gene complexes: white (1-1.5; 3C1.5) and bithorax (3-58.8; 89E1-4) in Drosophila melanogaster. Certain mutations of these complexes have been shown to behave in a synapsis-dependent fashion. That is, certain bithorax and white genotypes exhibit one level of expression when the two copies of these loci are able to synapse in somatic tissues and another level when heterozygosity for chromosomal rearrangements interferes with their ability to pair. Such phenomena are termed transvection effects by Lewis (1954). In the case of the white locus, asynapsis leads to a more normal state, whereas at bithorax, asynapsis leads to a more mutant phenotype. Recently, a third case of transvection was described at the decapentaplegic (2-4.0; 22F1-3) gene complex (Gelbart 1982); phenomenologically, it is very similar to transvection at bithorax. In this report, we demonstrate that zeste mutations can also interact with those decapentaplegic mutations that exhibit transvection effects. In addition, we present more information on the zeste interactions with white and bithorax. Interactions with zeste may be diagnostic of loci that can exhibit transvection effects. However, different groups of zeste alleles interact with each complex. z1 interacts with white, za alleles interact with bithorax and all tested zeste mutants interact with decapentaplegic. These differential effects of zeste mutations may be a reflection of the neomorphic nature of the z1 allele.
MUTATIONS IN THE PHO80 GENE CONFER PERMEABILITY TO 5'-MONONUCLEOTIDES IN SACCHAROMYCES CEREVISIAE
Authors: Bisson Linda F , Thorner Jeremy 
Published: January 2021

ABSTRACT
Yeast mutants permeable to dTMP (tup) were selected and two new complementation groups (tup5 and tup7) were identified. Assay of the levels of both acid and alkaline phosphatase in cells grown under either repressing (5 mm PO4 -3) or derepressing (0.03 mm PO4 -3) conditions indicated that, in general, tup mutations cause cells to be defective in their regulation of phosphatase synthesis. In addition, three of the tup mutations (tup1, tup4 and tup7) displayed markedly elevated rates of inorganic phosphate transport. The tup7 locus was found to be tightly centromere-linked on the right arm of chromosome XV, and was shown to be allelic with the pho80 regulatory locus on the basis of both genetic and biochemical criteria. Analysis of other mutations known to affect phosphatase levels (pho) indicated that some also conferred permeability to dTMP. Possible allelic relationships between tup genes and certain of these pho mutations are discussed. Regardless of the culture conditions, wild-type strains were not permeable to dTMP; in contrast, it was found in the course of this work that normal yeast cells were permeable to dUMP and that dUMP permeability was regulated by the concentration of inorganic phosphate present in the medium used to grow the cells. Thus, permeability to 5′-mononucleotides appears to be under coordinate control with phosphatase synthesis.
PROTEIN POLYMORPHISMS, SEGREGATION IN GENETIC CROSSES AND GENETIC DISTANCES AMONG FISHES OF THE GENUS XIPHOPHORUS (POECILIIDAE)
Authors: Morizot Don C , Siciliano Michael J 
Published: January 2021

ABSTRACT
The products of 49 protein-coding loci were examined by starch gel electrophoresis for populational variation in six species of Xiphophorus fishes and/or segregation in intra- and interspecific backcross and intercross hybrids. Electrophoretic variation was observed for 29 of the 35 locus products in a survey of 42 population samples. The highest frequency of polymorphic loci observed in noninbred populations was 0.143. After ten or more generations of inbreeding, all loci studied were monomorphic. Inbred strains generally exhibited the commonest electrophoretic alleles of the population from which they were derived. An assessment of genetic distances among Xiphophorus populations reflected classical systematic relationships and suggested incipient subspeciation between X. maculatus from different drainages as well as several species groups. Thirty-three loci were analyzed with respect to segregation in hybrids. The goodness of fit of segregations to Mendelian expectations at all loci analyzed (except loci in linkage group I) is interpreted as evidence for high genetic compatibility of the genomes of Xiphophorus species. It is anticipated that these data will result in a rapid expansion of the assignment of protein-coding loci to linkage groups in these lower vertebrate species.
ORGANIZATION AND EVOLUTION OF THE MAMMALIAN GENOME: I. POLYMORPHISM OF H-2 LINKED LOCI
Authors: Nadeau Joseph H , Collins Robert L , Klein Jan 
Published: January 2021

ABSTRACT
To test the hypothesis that the H-2 polymorphism is adaptive, the degree of polymorphism of loci linked to the H-2 complex on chromosome 17 of the house mouse was compared to the degree of polymorphism of loci located on other chromosomes. Published theoretical analyses show that polymorphisms subject to natural selection usually reduce the polymorphism of linked neutral loci. The first test of the hypothesis was based on data obtained from a survey of the polymorphism of 12 isozyme-encoding loci in wild house mice from Europe, North Africa and South America. Results of this test showed that, on the average, H-2-linked loci were as polymorphic as loci located on other chromosomes. In fact, the data suggested that H-2 linked loci might be more polymorphic than other loci. To test this hypothesis more rigorously, data for the 12 isozyme-encoding loci were augmented with data from published surveys of the polymorphisms of 59 loci in house mice from Europe and North America. Results of these tests showed that polymorphic loci linked to the H-2 complex tended to be more, rather than less, polymorphic than loci located on other chromosomes. The cluster of highly polymorphic loci seems to be related to linkage of these loci to the highly polymorphic H-2 complex, but the way in which the influence is exerted could not be readily explained.
SEQUENCE OF CENTROMERE SEPARATION: ROLE OF CENTROMERIC HETEROCHROMATIN
Authors: Vig Baldev K 
Published: January 2021

ABSTRACT
The late metaphase-early anaphase cells from various tissues of male Mus musculus, M. poschiavinus, M. spretus, M. castaneus, female and male Bos taurus (cattle) and female Myopus schisticolor (wood lemming) were analyzed for centromeres that showed separation into two daughter centromeres and those that did not show such separation. In all strains and species of mouse the Y chromosome is the first one to separate, as is the X or Y in the cattle. These sex chromosomes are devoid of constitutive heterochromatin, whereas all autosomes in these species carry detectable quantities. In cattle, the late replicating X chromosome appears to separate later than the active X. In the wood lemming the three pairs of autosomes with the least amount of centromeric constitutive heterochromatin separate first. These are followed by the separation of seven pairs of autosomes carrying medium amounts of constitutive heterochromatin. Five pairs of autosomes with the largest amounts of constitutive heterochromatin are the last in the sequence of separation. The sex chromosomes with medium amounts of constitutive heterochromatin around the centromere, and a very large amount of distal heterochromatin, separate among the very late ones but are not the last. These observations assign a specific role to centromeric constitutive heterochromatin and also indicate that nonproximal heterochromatin does not exert control over the sequence in which the centromeres in the genome separate. It appears that qualitative differences among various types of constitutive heterochromatin are as important as quantitative differences in controlling the separation of centromeres.
NEW SUPPRESSORS OF FRAMESHIFT MUTATIONS IN SALMONELLA TYPHIMURIUM
Authors: Kohno Tadahiko , Bossi Lionello , Roth John R 
Published: January 2021

ABSTRACT
Several new types of suppressor mutants have been isolated. These were identified among revertants of mutants originally generated by mutagens other than the acridine-derived ICR191. The new suppressors correct mutations other than those with runs of C or G which are recognized by the previously described suppressors. Several frameshift mutations are corrected by more than one suppressor type. Apparently, the DNA base sequence near these mutant sites includes sites of action for several distinct suppressor types.
MALE PHENOTYPES AND MATING EFFICIENCY IN CAENORHABDITIS ELEGANS
Authors: Hodgkin Jonathan 
Published: January 2021

ABSTRACT
Mating behavior in adult male nematodes can be assayed by mating efficiency, i.e., the number of cross progeny sired by males under standard conditions. Mutant males from 220 strains, representing most of the known complementation groups of C. elegans, have been examined for mating efficiency and for anatomical abnormalities of the specialized male copulatory organs. These data extend the phenotypic description of these mutants and indicate what anatomical and behavioral components are necessary for the ability to mate successfully. Also, mutants with specific defects in the male were sought by establishing superficially wild-type hermaphrodite stocks after mutagenesis and testing the males segregated by these stocks for mating efficiency. Forty-nine of 1119 stocks yielded abnormal males. Seventeen were characterized in detail and found to be abnormal in sensory behavior (carrying mutations in the genes che-2 or che-3) or male genital anatomy (carrying mutations in one of the genes mab-1 to mab-10). Four of the mab (male abnormal) genes affect specific postembryonic cell lineages.
LOCATION OF THE LSP-1 GENES IN DROSOPHILA SPECIES BY IN SITU HYBRIDIZATION
Authors: Brock Hugh W , Roberts David B 
Published: January 2021

ABSTRACT
The locations of the larval serum protein one (LSP-1) α, β and γ genes were determined in Drosophila melanogaster and in 14 other species of Drosophila by in situ hybridization to polytene chromosomes. The LSP-1 α gene mapped to bands 11B on the X chromosome, the LSP-1 β gene mapped to bands 21D-E on chromosome 2L, and the LSP-1 γ gene mapped to band 61A in all the melanogaster subgroup species. In eight other species, both the LSP-1α and β genes mapped to one site on Muller's element E which corresponds to chromosome 3R of D. melanogaster. No hybridization of LSP-1 γ was detected in these eight species. Restriction enzyme digestion and analysis of genomic DNA by filter transfer hybridization confirmed the presence of LSP-1 α-like and β-like genes in seven of these species. These results are discussed with respect to conservation of the chromosomal elements in the genus Drosophila.
A MAJOR ROLE FOR BACTERIOPHAGE T4 DNA POLYMERASE IN FRAMESHIFT MUTAGENESIS
Authors: Ripley Lynn S , Shoemaker Nadja B 
Published: January 2021

ABSTRACT
T4 DNA polymerase strongly influences the frequency and specificity of frameshift mutagenesis. Fifteen of 19 temperature-sensitive alleles of the DNA polymerase gene substantially influenced the reversion frequencies of frameshift mutations measured in the T4 rII genes. Most polymerase mutants increased frameshift frequencies, but a few alleles (previously noted as antimutators for base substitution mutations) decreased the frequencies of certain frameshifts while increasing the frequencies of others. The various patterns of enhanced or decreased frameshift mutation frequencies suggest that T4 DNA polymerase is likely to play a variety of roles in the metabolic events leading to frameshift mutation. A detailed genetic study of the specificity of the mutator properties of three DNA polymerase alleles (tsL56, tsL98 and tsL88) demonstrated that each produces a distinctive frameshift spectrum. Differences in frameshift frequencies at similar DNA sequences within the rII genes, the influence of mutant polymerase alleles on these frequencies, and the presence or absence of the dinucleotide sequence associated with initiation of Okazaki pieces at the frameshift site has led us to suggest that the discontinuities associated with discontinuous DNA replication may contribute to spontaneous frameshift mutation frequencies in T4.
COMPLEMENTATION AND PRELIMINARY LINKAGE ANALYSIS OF ZYGOTE MATURATION MUTANTS OF THE HOMOTHALLIC ALGA, CHLAMYDOMONAS MONOICA
Authors: VanWinkle-Swift Karen P , Burrascano Cynthia G 
Published: January 2021

ABSTRACT
Sexual reproduction in Chlamydomonas monoica is homothallic: pair formation and cell fusion occur in clonal culture and give rise to a heavily walled diploid zygospore. During maturation of the young zygote, a distinctive "primary zygote wall" is released before the development of the highly reticulate zygospore wall. Using ethyl methanesulfonate and ultraviolet irradiation as mutagens, we have isolated 19 maturation-defective (zym) mutant strains which upon self-mating produce inviable zygotes. These zygotes fail to release a primary zygote wall, fail to develop the normal zygospore wall, and eventually undergo spontaneous lysis. In nearly all cases, the mutations appear to be expressed only in the diploid zygote; pleiotropic effects on vegetative cell growth or morphology are not evident.—Complementation testing performed on 17 of these mutants indicates that all are recessive and that they define seven distinct complementation groups. Preliminary tetrad analysis of two-factor and multifactor zym crosses provides no evidence for physical clustering of the maturation genes, and instead suggests that they are widely distributed throughout the nuclear genome.
MODELS OF EVOLUTION OF REPRODUCTIVE ISOLATION
Authors: Nei Masatoshi , Maruyama Takeo , Wu Chung-I 
Published: January 2021

ABSTRACT
Mathematical models are presented for the evolution of postmating and premating reproductive isolation. In the case of postmating isolation it is assumed that hybrid sterility or inviability is caused by incompatibility of alleles at one or two loci, and evolution of reproductive isolation occurs by random fixation of different incompatibility alleles in different populations. Mutations are assumed to occur following either the stepwise mutation model or the infinite-allele model. Computer simulations by using Itô's stochastic differential equations have shown that in the model used the reproductive isolation mechanism evolves faster in small populations than in large populations when the mutation rate remains the same. In populations of a given size it evolves faster when the number of loci involved is large than when this is small. In general, however, evolution of isolation mechanisms is a very slow process, and it would take thousands to millions of generations if the mutation rate is of the order of 10-5 per generation. Since gene substitution occurs as a stochastic process, the time required for the establishment of reproductive isolation has a large variance. Although the average time of evolution of isolation mechanisms is very long, substitution of incompatibility genes in a population occurs rather quickly once it starts. The intrapopulational fertility or viability is always very high. In the model of premating isolation it is assumed that mating preference or compatibility is determined by male- and female-limited characters, each of which is controlled by a single locus with multiple alleles, and mating occurs only when the male and female characters are compatible with each other. Computer simulations have shown that the dynamics of evolution of premating isolation mechanism is very similar to that of postmating isolation mechanism, and the mean and variance of the time required for establishment of premating isolation are very large. Theoretical predictions obtained from the present study about the speed of evolution of reproductive isolation are consistent with empirical data available from vertebrate organisms.
EVOLUTION OF TRANSPOSONS: NATURAL SELECTION FOR Tn5 IN ESCHERICHIA COLI K12
Authors: Biel Susan Wurster , Hartl Daniel L 
Published: January 2021

ABSTRACT
A novel in vivo effect of the transposable element Tn5 has been observed in chemostats when certain isogenic Tn5 and non-Tn5 strains of Escherichia coli compete for a limiting carbon source in the absence of kanamycin. The Tn5-bearing strain has a more rapid growth rate and increases in frequency from 50% to 90% within the first 15 to 20 generations. The effect occurs when Tn5 is inserted at a variety of chromosomal locations or when the element is carried by an episome, but it is strain specific, having been observed in two out of three strains examined. (For reasons unknown, the effect has not been observed with derivatives of strain CSH12.) Although the growth-rate advantage of Tn5 is independent of nutrient concentration and generation time, it can be reduced by prior adaptation of the strains to limiting conditions, and the amount of reduction is proportional to the length of prior adaptation. The growth-rate effect is evidently not caused by beneficial mutations induced by Tn5 transposition, as Tn5-bearing strains selected in chemostats retain their initial Tn5 position and copy number. However, the effect does not occur in Tn5-112, a transpositionless deletion mutation missing the transposase-coding region of the right-hand IS sequence flanking the element. Since Tn5-112 retains a functional kanamycin-phosphotransferase gene, this gene is not responsible for the growth-rate effect. Thus, the effect evidently requires transposase function, but it does not involve actual transposition of the intact element. Altogether, these data provide a mechanism for the maintenance of Tn5 in bacterial populations in the absence of kanamycin, and they suggest a model for the proliferation and the maintenance of IS sequences and transposable elements in the absence of other identifiable selection pressures.
A PRODUCT OF THE TN5 TRANSPOSASE GENE INHIBITS TRANSPOSITION
Authors: Lowe John B , Berg Douglas E 
Published: January 2021

ABSTRACT
The bacterial transposon Tn5 possesses a regulatory mechanism that allows it to move with higher efficiency when it is first introduced into a cell than after it is established. Tn5 is a composite transposable element containing inverted repeats of two nearly identical elements, IS50R, which encodes the transposase protein necessary for Tn5 movement, and IS50L which contains an ochre mutant allele of the transposase gene. Data presented here show that Tn5 transposition is inhibited about 50-fold in cells of Escherichia coli which already carry IS50R in the multicopy plasmid pBR322. If the cells contain a plasmid carrying either IS50L instead of IS50R, or derivatives of IS50R in which the transposase gene has been mutated, little if any inhibition of Tn5 transposition is found. Although inhibition had previously been hypothesized to require interaction between the products of IS50L and IS50R, our results show that IS50R alone is sufficient to mediate inhibition and suggest that the inhibitor is a product of the transposase gene itself.