bluuebunny/crossref_metadata_2025 huggingface dataset:
FEEDBACK-INSENSITIVE MUTANTS OF THE GENE FOR THE TYROSINE-INHIBITED DAHP SYNTHETASE IN YEAST
Authors: Meuris Pierre
Published: January 2021

A yeast strain lacking the phenylalanine-sensitive DAHP synthetase exhibits a tyrosine-inhibited phenotype. Reversions from this phenotype were selected. They were the result of mutations affecting the tyrosine-sensitive DAHP synthetase which became insensitive to feedback inhibition, as shown by genetic and enzymatic studies. The feedback-insensitive mutations were located at five different sites scattered on the map of the aro4 gene.
SEX-LINKED AUXOTROPHIC AND PUTATIVE AUXOTROPHIC MUTANTS OF DROSOPHILA MELANOGASTER
Authors: Falk D R , Nash David
Published: January 2021

Thirty-two mutants with improved growth response on a yeast-sucrose compared with a defined medium have been characterized with respect to ribonucleoside supplementability. Twenty mutants respond to either pyrimidine ribonucleoside. Four mutants respond to one or both purine ribonucleosides. Eight mutants ("putative" auxotrophs) do not respond to dietary RNA supplementation. Mapping and complementation studies suggest that eleven loci are represented: one, rudimentary, probably accounts for all pyrimidine requirers; there are three purine loci and seven at which the putative auxotrophs are found.
DEVELOPMENT IN GENETIC MOSAICS OF ARISTAPEDIA, A HOMOEOTIC MUTANT OF DROSOPHILA MELANOGASTER
Authors: Postlethwait J H , Girton J R
Published: January 2021

Development of the homoeotic mutation, aristapedia (ss  a), was investigated by means of genetic mosaics. The wild-type alleles of aristapedia and the bristle markers yellow, singed, and forked were removed from cells at different times in development by X-ray induced somatic crossing-over. The phenotype of the resulting clones was examined in order to ascertain whether it was leg or antenna. The y sn f; ssa clones showed a leg phenotype if induced before the mid-third instar, but showed an antennal phenotype if induced after this time. Late non-expression of ss  a may be due either to an influence of surrounding ss  + tissues on the small ss  a clones, or to a persistence of the effect of ss  + for one or two cell generations after it is removed from a cell line.
THE CYTOGENETIC ANALYSIS OF A FRACTURED GENE IN DROSOPHILA
Authors: Welshons W J
Published: January 2021

The data presented in this study are derived from the analyses of Notch mutants known to be associated with visible cytological deficiencies. One mutant, Df(1)N62b1, described as a right-side deficiency, bears a deletion that apparently initiates within the Notch locus and extends to the right as far as the locus of dm. Recombination experiments using heterozygotes of Df(1)N62b1 with a series of intragenic point mutants within the Notch cistron suggest that this deficiency represents a deletion for the right-end portion of the gene. A consideration of the cytology of Df(1)N62b1 supports the cytogenetic inference that, if a Notch locus-3C7 relationship is valid, the missing portion of the gene as assayed by recombination experiments has an interband position between 3C7 and 8.—The data derived from two left-side deficiencies with a genetic lesion in Notch and a deletion extending to w are somewhat equivocal, but they do support the presumed Notch locus-3C7 band relationship and thereby enhance the likelihood that Df(1)N62b1 is correctly interpreted.—Cytogenetic information presently available suggests that, although a significant portion of the Notch cistron has a position on the salivary map identified as interband 3C7 to 8, the 3C7 band is part of the total picture of the Notch gene.
EXCHANGE WITHIN HETEROZYGOUS INVERSIONS IN DROSOPHILA MELANOGASTER
Authors: Robbins Leonard G
Published: January 2021

The exchange behavior of non-attached, whole arm, X chromosome inversions was reexamined using nondisjunction in XXY females as an indirect measure of the frequency of nonexchange tetrads. Crossing over is quite normal in these inversion heterozygotes and is independent of the arrangement of the basal heterochromatin.
GENETIC ANALYSIS OF THE RECIPROCAL TRANSLOCATION T2(I;VIII) OF ASPERGILLUS USING THE TECHNIQUE OF MITOTIC MAPPING IN HOMOZYGOUS TRANSLOCATION DIPLOIDS
Authors: Ma Gloria C L , Käfer Etta
Published: January 2021

A UV-induced sulphite-requiring mutant (sD50) consistently shows mitotic linkage to groups I and VIII in haploids from heterozygous mapping diploids. This linkage was found to be due to a reciprocal translocation T2(I;VIII) which could not be separated from the sulphite requirement in about 100 tested progeny from heterozygous crosses, and both may well have been induced by the same mutational event. T2(I;VIII) is the first case of a reciprocal translocation in Aspergillus which showed meiotic linkages between markers of different linkage groups, and, in addition, involved chromosome arms containing markers suitable for complete mapping by the technique of mitotic recombination in homozygous translocation diploids.—Using various selective markers, haploid segregants and diploid crossovers of all possible types were isolated from homozygous translocation diploids. (1) Haploid segregants showed new linkage relationships in T/T diploids: all available markers of VIII now segregated as a group with the majority of the markers of I, exceptfor the markers of the left tip of I. These formed a separate linkage group and are presumably translocated to VIII. (2) Diploid mitotic crossovers confirmed this information nd shhowed that the orientation of the translocated segments was unchanged. These findings conclusively demonstrate that T2(I; VIII) is a reciprocal translocation due to an exchange of the left tip of group I with the long right arm of group VIII.—Since the position of the break on VIIIR was found to be at sD50 this marker could be used to map the break on IL by meiotic recombination in heterozygous crosses. In addition, such crosses showed reduced recombination around the breaks, so that it was possiblc to sequence markers which normally are barely linked.
THE INTERACTION OF KNOBS AND B CHROMOSOMES OF MAIZE IN DETERMINING THE LEVEL OF RECOMBINATION
Authors: Chang C C , Kikudome Gary Y
Published: January 2021

Enhancement of recombination by B chromosomes is influenced by the kind of heterochromatic knob present in or near the tested region of the A chramosomes. In homomorphic chromosome 9 bivalents of KS/KS constitution, double exchanges were increased at the expense of singles, but in the K*/Ks heteromorphs there was a gain in both single and double exchanges at the expense of no-exchange tetrads. Modification of the B chromosome enhancement in different knob compounds was observed only in the megasporocytes.—Different frequencies of recombination are found in plants with odd and even numbers of B Chromosomes; this effect is especially striking in the megasporocytes. The modification in recombination produced by an odd or even number of B chromosomes is a function of the interaction of a particular region and the knob constitution. Odd numbers of B chromosomes were more effective than even numbers in causing increased recombination.—It is concluded that heterochromatic knobs and the essentially heterochromatic supernumeraries may interact in the process of crossing over, with the level of recombination determined in part by knob constitution.
ALTERNATE-1 AND ALTERNATE-2 DISJUNCTIONS IN HETEROZYGOUS RECIPROCAL TRANSLOCATIONS
Authors: Endrizzi J E
Published: January 2021

Alternate-1 and alternate-2 orientation of chromosomes, as well as the two types of adjacent orientation, were observed cytologically in the ring configurations of three reciprocal translocation heterozygotes of Gossypium hirsutum L. The observations indicate that the two types of alternate orientation should be characteristic of ring-forming translocations.
THE GENETICS OF CAENORHABDITIS ELEGANS
Authors: Brenner S
Published: January 2021

Methods are described for the isolation, complementation and mapping of mutants of Caenorhabditis elegans, a small free-living nematode worm. About 300 EMS-induced mutants affecting behavior and morphology have been characterized and about one hundred genes have been defined. Mutations in 77 of these alter the movement of the animal. Estimates of the induced mutation frequency of both the visible mutants and X chromosome lethals suggests that, just as in Drosophila, the genetic units in C.elegans are large.
EVIDENCE FOR THE INVOLVEMENT OF SERINE TRANSHYDROXYMETHYLASE IN SERINE AND GLYCINE INTERCONVERSIONS IN SALMONELLA TYPHIMURIUM
Authors: Stauffer George V , Brenchley Jean E
Published: January 2021

Salmonella typhimurium can normally use glycine as a serine source to support the growth of serine auxotrophs. This reaction was presumed to occur by the reversible activity of the cnzyme, serine transhydroxymethylase (E. C. 2. 1. 2. 1; L-serine: tetrahydrofolic-5, 10 transhydroxymethylase), which is responsible for glycine biosynthesis. However, this enzyme had not been demonstrated to be solely capable of synthesizing serine from glycine in vivo. The isolation and characterization of a mutant able to convert serine to glycine but unable to convert glycine to serine supports the conclusion that a single enzyme is involved in this reversible interconversion of serine and glycine. The mutation conferring this phenotype was mapped with other mutations affecting serine transhydroxymethylase (glyA) and assays demonstrated reduced activities of this enzyme in the mutant.
RECOMBINANTS BETWEEN CLOCK MUTANTS OF CHLAMYDOMONAS REINHARDI
Authors: Bruce Victor G
Published: January 2021

Mutants affecting the period length of the biological clock in Chlamydomonas reinhardi have been isolated and a start has been made on analyzing the genetics of this system. In four mutants, the long period characteristic seems to be controlled by single genes at separate loci. Crosses between single mutants, as well as crosses involving three or four mutant genes, yielded progeny with periods characteristic of the parents as well as recombinant types, including normal period (wild type) and extra-long periods (double, triple and quadruple mutants). It was found that the period lengthening effect is additive; that is, the period of double mutants is lengthened by the sum of the period lengthening of the single mutants.
GENE CONVERSION OF DELETIONS IN THE HIS4 REGION OF YEAST
Authors: Fink G R , Styles C A
Published: January 2021

A selection procedure has been devised which allows the recovery of deletions of the his4 region of Saccharomyces cerevisiae. Many deletions were obtained by this procedure and were characterized genetically and biochemically. These deletions permit the construction of a linear map of the his4A and his4B region. A deletion which was large on this genetic map reduced the size of the his4 gene product. Tetrad analyses revealed that deletions can affect the conversion frequency of other alleles at his4. Analysis of reciprocal recombination in conversion tetrads showed that the order of genes on chromosome III is: centromere-leuZ-his4A-his4C. This means that in his4 transcription and translation proceed away from the centromere.
ENZYME VARIABILITY IN NATURAL POPULATIONS OF DAPHNIA MAGNA III. GENOTYPIC FREQUENCIES IN INTERMITTENT POPULATIONS
Authors: Hebert Paul D N
Published: January 2021

In temporary habitats populations of the cyclical parthenogen, Daphnia magna, are re-established each year from sexual eggs and reproduce partheno-genetically for two or at most three generations. The genetic effects of this breeding system have been investigated by analyzing allozyme frequencies in nineteen intermittent populations—Genotypic frequencies at polymorphic loci were ordinarily found to be in good agreement with Hardy-Weinberg proportions and disequilibria between loci were not observed. Although significant changes in gene frequencies were observed both during and between successive cycles, there was no evidence of the marked instability of genotype frequencies characteristic of permanent populations. The recombinational degradation of genotypes at the end of each annual cycle in temporaly habitats effectively prevents the genotypic structuring which develops when continued parthenogenesis is possible.
MICRODIFFERENTIATION IN A NATURAL POPULATION OF DROSOPHILA MELANOGASTER TO ALCOHOL IN THE ENVIRONMENT
Authors: McKenzie J A , Parsons P A
Published: January 2021

Strains of D. melanogaster derived from a vineyard population were more resistant to alcohol in the environment than strains from a population derived from an area removed from the vineyard. Within the vineyard population those strains most closely associated with alcohol in the environment in the cellar were more resistant than those collected outside the cellar. There was evidence of gene flow between the inside and outside cellar components of this population, but microdifferentiation had occurred within the cellar in spite of this. The adaptation appears to be independent of the ADH system and involves both additive and dominance genetic effects. D. simulans, a species not found in the cellar and susceptible to the presence of alcohol, showed no differentiation between vineyard and removed populations.
THE DISTRIBUTION OF CROSSOVERS ALONG UNREPLICATED LAMBDA BACTERIOPHAGE CHROMOSOMES
Authors: Stahl Franklin W , McMilin Kenneth D , Stahl Mary M , Crasemann Jean M , Lam Stephen
Published: January 2021

The distribution of crossovers along unreplicated chromosomes of bacteriophage lambda has been examined by determining the density distributions and genotypes of particles in the progenies of crosses of density-labeled by ordinary parents in the presence of genetic blocks to replication. The Red and Rec systems combined produce crossovers primarily near the ends (especially the right end) of the chromosome. Removal of the generalized lambda recombination functions by red and gam mutations results in loss of these terminal crossovers; coupled with this loss is a disappearance of the differential dependence of recombination frequencies in terminal and central intervals on DNA synthesis. Removal of the bacterial system by a recA mutation results in severe depression of crossing over among unreplicated phage, with the few recombinants produced by the lambda system occurring near the right end.
MARKER DISCRIMINATION AND MUTAGEN-INDUCED ALTERATIONS IN PNEUMOCOCCAL TRANSFORMATION
Authors: Tiraby Jean-Gérard , Fox Maurice S
Published: January 2021

Nitrous acid-induced and hydroxylamine-induced chemical alterations in transforming DNA result in the loss of biological activity and in mutagenesis. The function responsible for the discrimination between high efficiency and low efficiency markers in pneumococcal transformation, and for the elimination of a substantial fraction of spontaneously occurring mutational events, does not appear to act on integrated DNA carrying these chemical alterations. The chemical modifications result in mutations that are evident among bacteria transformed with the treated DNA. Fusidic acid-resistant mutants isolated in this way have been shown to be predominantly of the low efficiency class. We have previously reported that most mutations of spontaneous origin occurring in this locus are of the high efficiency class, and have suggested that discrimination results from the elimination of specific classes of base pair mismatches that occur as intermediates in transformation. It would appear that the base pair mismatches most effectively eliminated in the discriminating strain of pneumococcus are those of the A:C and G:T type and that the immediate product of transformation with mutagenized DNA involves intermediates that are not recognized as A:C or G:T by the discrimination system.
DOMINANCE RELATIONSHIPS BETWEEN TWO ALLELIC GENES CONTROLLING GLYCOSYLTRANSFERASES WITH DIFFERENT SUBSTRATE SPECIFICITY IN MELANDRIUM
Authors: van Brederode J , van Nigtevecht G
Published: January 2021

Genetical analysis showed that the genes gG and gX, which control, respectively, the glucosylation and xylosylation of the 7-hydroxyl group of isovitexin in the petals of Melandrium, are alleles. In petal extracts of plants possessing the gene gX an enzyme was present which catalyzed the transfer of the xylose moiety of UDP-xylose to the 7-hydroxyl group of isovitexin. The xylosyl-transferase controlled by the gene gX had a "true Km value" of 0.77 mM for UDP-xylose. The "true Km value" for isovitexin was << 0.04 mM. The transfer of glucose from UDP-glucose to the 7-hydroxyl group of isovitexin is catalyzed by the enzyme controlled by gene gG. In plants possessing both the alleles gG and gX, only the gene product of gG, i.e., isovitexin 7-O-glucoside, was found. In this respect gG is dominant over allele gX. In petal extracts of these gGgX plants, however, besides UDP-glucose: isovitexin 7-O-glucosyltransferase, also UDP-xylose: isovitexin 7-O-xylosyltransferase could be detected. This means that the dominance is not a consequence of transcriptional and/or translational control. Enzyme kinetic experiments showed that inhibition of the xylosyltransferase by the endproduct of the glucosyltransferase did not occur. Comparison of the enzyme kinetic parameters revealed that the dominance is probably caused by differences in Vmax between the two enzymes, both working at saturating isovitexin concentrations. A competition model is suggested which explains why the amount of isovitexin 7-O-glucoside in gGgG plants and the amount of isovitexin 7-O-xyloside in gXgX plants are about the same, whereas in gGgX plants isovitexin 7-O-xyloside escapes detection. The differences in distribution of the isovitexin glycosylation genes in the two species M. album and M. dioicum are discussed.
THE GENETIC IDENTIFICATION OF A HETEROCHROMATIC SEGMENT ON THE X CHROMOSOME OF DROSOPHILA MELANOGASTER
Authors: Parry Dilys M , Sandler L
Published: January 2021

An autosomal euchromatic maternal-effect mutant, abo (= abnormal oocyte), interacts with, or regulates the activity of, the heterochromatin of the sex chromosomes of Drosophila melanogaster. It is shown that this interaction or regulation with the X chromosome involves a specific heterochromatic locus or small region that maps to the distal penultimate one-eighth of the basal X-chromosome heterochromatic segment.
ASSOCIATION OF ALLELES OF THE MALIC DEHYDROGENASE LOCUS WITH A PERICENTRIC INVERSION IN DROSOPHILA ROBUSTA
Authors: Prakash Satya , Levitan Max
Published: January 2021

Associations of Malic dehydrogenase alleles with the third chromosome arrangement 3R and the pericentric arrangement 3L-R are described. Even though significant associations between alleles and inversions exist within a population, there is an overall similarity in MDH allele frequencies in different populations inspite of large differences in inversion frequencies.
CORRELATIONS IN MULTI-LOCUS GENETIC SYSTEMS: A MATHEMATICAL MODEL
Authors: Falk C T , Falk H
Published: January 2021

A spin model with parallels to a multi-locus genetic model is presented which makes it possible to calculate the correlation between allelic states at any two loci in a population at equilibrium. The main features are: (1) The decay of correlation with distance may be expressed essentially as a linear combination of two exponentials, one of which dominates when the two loci are sufficiently far apart. (2) The correlation between two loci a specified distance apart is increased as the number of loci in the entire system increases. The results are compared with those of other theoretical models and discussed in the light of available experimental data. Possible ways of generalizing the model are outlined. However, additional experimental data is clearly needed to indicate the genetic relevance of work of this nature.
REVERTANTS AND SECONDARY arom-2 MUTANTS INDUCED IN NON-COMPLEMENTING MUTANTS IN THE arom GENE CLUSTER OF NEUROSPORA CRASSA
Authors: Case Mary E , Giles Norman H
Published: January 2021

Extensive genetical and biochemical studies have been performed with revertants and secondary arom-2 mutants induced in two different primary non-complementing mutants which map within the arom gene cluster of Neurospora crassa. These studies indicate that mutant M54 but not M25 can revert by super-suppressor mutations in unlinked genes, thus confirming previous evidence that M54 contains a nonsense codon. At least three new super suppressors of M54 have been detected. All four super suppressors (including one previously detected) when combined with M54 result in high levels of all five of the arom enzymic activities in the form of arom multienzyme complexes very similar to (but not necessarily identical with) that in wild type (WT).—Evidence has also been obtained that the two non-complementing mutants can yield revertants which appear to result from true back mutations and produce arom aggregates essentially indistinguishable from that of WT. In addition, M25, but not M54, when plated on quinic acid yields revertants (secondary mutants) some of which are phenotypically indistinguishable from arom-2 primary mutants and others of which, although also mapping within the arom-2 gene, exhibit unusual properties. Genetic evidence indicates that the M25 secondary mutants are localized within the arom-2 gene, but that they arise from mutational events more complex than ones resulting in single base pair changes in the M25 codon.—The recovery of secondary arom-2 mutants as revertants of non-complementing arom mutants provides strong evidence, independent of earlier recombination data, that non-complementing arom mutants are located within the arom-2 structural gene of the arom gene cluster. In addition, the occurrence and characteristics of these secondary arom-2 mutants provide strong evidence, independent of the results with nonsense suppressors, that the arom gene cluster is transcribed, beginning with the arom-2 gene, as a single polycistronic messenger ribonucleic acid (mRNA) molecule which is subsequently translated into the arom multienzyme complex.
CHROMOSOMAL LOCATION BY USE OF TRISOMICS AND NEW ALLELES OF AN ENDOPEPTIDASE IN ZEA MAYS
Authors: Nielsen Gunnar , Scandalios John G
Published: January 2021

An association was found earlier between the Ep1 gene locus coding for an endopeptidase and the endosperm color gene Y1 on chromosome 6 of Zea mays. By employing primary trisomics we have unequivocally placed the Ep1 gene on chromosome 6, closely linked to the Y1 locus. Additionally we describe new alleles at the Ep1 locus, and present evidence for the existence of a second endopeptidase system in maize.
EFFECTS OF DOSE ON THE INDUCTION OF DOMINANT-LETHAL MUTATIONS WITH TRIETHYLENEMELAMINE IN MALE MICE
Authors: Matter B E , Generoso W M
Published: January 2021

Dose effects of triethylenemelamine (TEM) in the induction of dominant-lethal mutations were studied at the early spermatozoon, midspermatid and spermatocyte stages. The pattern of effects on spermatocytes, unlike midspermatids and early spermatozoa, indicated possible cytotoxic damage, so for the determination of TEM dose-response curves in the induction of genetic damage only the data for midspermatids and early spermatozoa were used. The TEM dose-effect curves for those two stages differ markedly from ethyl methanesulfonate (EMS) dose-effect curves. Beginning with the lowest doses at which significant effects are observed, there is a considerably more rapid increase in dominant-lethal effects with dose of EMS than TEM. Another marked difference between the two compounds is in the ratio of the genetically effective dose (as measured by dominant-lethal mutations) to the lethal dose. The ratio is 1:100 for TEM and only 1:3.5 for EMS; thus, TEM is mutagenic far below its toxic level. Obviously, these results have important implications not only for our understanding of the nature of chemical induction and recovery of chromosomal aberrations but also for the practical problems of evaluating the mutagenic effects of chemicals.
DNA DAMAGE AND REPAIR IN EUKARYOTIC CELLS
Authors: Painter R B
Published: January 2021

Damage in DNA after irradiation can be classified into five kinds: base damage, single-strand breaks, double-strand breaks, DNA-DNA cross-linking, and DNA-protein cross-linking. Of these, repair of base damage is the best understood. In eukaryotes, at least three repair systems are known that can deal with base damage: photoreactivation, excision repair, and post-replication repair. Photoreactivation is specific for UV-induced damage and occurs widely throughout the biosphere, although it seems to be absent from placental mammals. Excision repair is present in prokaryotes and in animals but does not seem to be present in plants. Post-replication repair is poorly understood. Recent reports indicate that growing points in mammalian DNA simply skip past UV-induced lesions, leaving gaps in newly made DNA that are subsequently filled in by de novo synthesis. Evidence that this concept is oversimplified or incorrect is presented.—Single-strand breaks are induced by ionizing radiation but most cells can rapidly repair most or all of them, even after supralethal doses. The chemistry of the fragments formed when breaks are induced by ionizing radiation is complex and poorly understood. Therefore, the intermediate steps in the repair of single-strand breaks are unknown. Double-strand breaks and the two kinds of cross-linking have been studied very little and almost nothing is known about their mechanisms for repair.—The role of mammalian DNA repair in mutations is not known. Although there is evidence that defective repair can lead to cancer and/or premature aging in humans, the relationship between the molecular defects and the diseased state remains obscure.
PROTEIN SYNTHESIS DIRECTED BY THE RNA FROM A PLANT VIRUS IN A NORMAL ANIMAL CELL
Authors: Knowland John
Published: January 2021

RNA from tobacco mosaic virus can be translated inside oocytes of the frog Xenopus laevis. The main product is a polypeptide with a molecular weight of 140,000. There is no evidence for coat protein synthesis, and it is unlikely that the polypeptide that is made contains either a whole or a partial coat protein sequence.

The picture of translation of tobacco mosaic virus RNA obtained using oocytes is very much simpler than that found using cell-free protein-synthesizing systems, in which a great many polypeptides are made under the direction of tobacco mosaic virus RNA. The reasons for this difference are discussed, and the relative merits of in vivo and in vitro protein-synthesizing systems are compared.
EXPERIMENTAL STUDIES ON THE ORIGIN OF CULTIVATED RICE
Authors: Oka Hiko-Ichi
Published: January 2021

1) Contributions to the origin of cultivated rice made by the author and his colleagues were briefly reviewed under several headlines.—2) Two parallel series of evolution of cultivated species, the Asian form of Oryza perennis to O. sativa and O. breviligulata to O. glaberrima, were pointed out compared.—3) In both the two series, a continuous array of intergrades between wild and cultivated species is found in a particular region. The pattern of character variations among those intermediate plants was considered as indicating the evolutionary path, and the monophyletic origin of the Indica and Japonica types of O. sativa was discussed.—4) The conditions of establishment of a weedy form of O. perennis found in India were discussed. It was noticed that cultivation by man in itself works as a selective agent for cultivated types.
Chromosome-level reference genome of the European wasp spider Argiope bruennichi: a resource for studies on range expansion and evolutionary adaptation
Authors: Sheffer Monica M , Hoppe Anica , Krehenwinkel Henrik , Uhl Gabriele , Kuss Andreas W , Jensen Lars , Jensen Corinna , Gillespie Rosemary G , Hoff Katharina J , Prost Stefan
Published: January 2021

Background

Argiope bruennichi, the European wasp spider, has been investigated intensively as a focal species for studies on sexual selection, chemical communication, and the dynamics of rapid range expansion at a behavioral and genetic level. However, the lack of a reference genome has limited insights into the genetic basis for these phenomena. Therefore, we assembled a high-quality chromosome-level reference genome of the European wasp spider as a tool for more in-depth future studies.

Findings

We generated, de novo, a 1.67 Gb genome assembly of A. bruennichi using 21.8× Pacific Biosciences sequencing, polished with 19.8× Illumina paired-end sequencing data, and proximity ligation (Hi-C)-based scaffolding. This resulted in an N50 scaffold size of 124 Mb and an N50 contig size of 288 kb. We found 98.4% of the genome to be contained in 13 scaffolds, fitting the expected number of chromosomes (n = 13). Analyses showed the presence of 91.1% of complete arthropod BUSCOs, indicating a high-quality assembly.

Conclusions

We present the first chromosome-level genome assembly in the order Araneae. With this genomic resource, we open the door for more precise and informative studies on evolution and adaptation not only in A. bruennichi but also in arachnids overall, shedding light on questions such as the genomic architecture of traits, whole-genome duplication, and the genomic mechanisms behind silk and venom evolution.
Mantle serpentinization beneath a failed rift and post-spreading magmatism in the northeastern South China Sea margin
Authors: Liu Yutao , Li Chun-Feng , Wen Yonglin , Yao Zewei , Wan Xiaoli , Qiu Xuelin , Zhang Jia-zheng , Abbas Aqeel , Peng Xi , Li Gang
Published: January 2021

The post-spreading magmatic activities in the northeastern South China Sea (SCS) margin are very strong, evidenced by widely distributed high-velocity lower crust (HVLC) and numerous volcanoes. However, there are large contrasts in magmatic activities and crustal structure between the Southern Depression (TSD) of the Tainan Basin and the volcanic continental slope area further south. We analyse their crustal P-wave velocity structures based on a newly acquired wide-angle ocean bottom seismic data set. The Cenozoic strata below the TSD, a Cenozoic failed rift, are relatively thick (∼3–4.5 km) with velocities from 1.6 to 3.6–3.9 km s–1, whereas the Mesozoic strata are relatively thin (∼1–2.5 km) with velocities from 4.3 to 4.6–5.2 km s–1. In the TSD, magmatic activities are relatively weak and the crust is severely thinned (∼4 km). The crust is 9–15 km thick below the volcanic continental slope area, which shows extensive volcanism. We identified HVLC below the failed rift of the TSD (Zone 1) and attributed it to mantle serpentinization, whereas the imaged HVLC below the volcanic continental slope (Zone 3) and HVLC adjacent to the failed rift of the TSD (Zone 2) are due to post-spreading magmatic underplating/intrusions. At the model distance ∼90 km, lateral transition from magmatic underplating/intrusions to mantle serpentinization occurred abruptly. We concur that post-spreading cooling and thermal contraction in the nearby SCS oceanic lithosphere can trigger decompressive melting and deformation in the thinned continental slope zone. Our study shows that, in addition to mantle serpentinization in the continent–ocean transition (COT) zone, mantle can also be serpentinized below the rift during early-stage rifting. Weak syn-rifting magmatism and mantle serpentinization below the failed rift support that the northeastern SCS has a magma-poor margin.
Family Law
Authors: Hodgson Roiya
Published: January 2021

Family Law takes a highly practical, student-centred approach to the essential law and procedure at the heart of family law. Providing a comprehensive guide to the subject, it focuses on relationship breakdown, money and property, children, and domestic abuse. A concise writing style and short chapters ensure focused learning, while chapter summaries and self-test questions help students to consolidate their knowledge and identify areas for further study. Throughout the book, case studies and examples are used, demonstrating how family law applies in practice and helping to prepare students for their future careers. The book also features diagrams and flowcharts throughout, helping to improve understanding of complex processes or areas of difficulty. Topics that are covered include: family law practice and the first interview; public funding; alternative dispute resolution in family law; judicial separation and nullity; divorce; defences to divorce; jurisdiction; procedure for a matrimonial order; the Civil Partnership Act 2004; dissolution of a civil partnership; financial orders following divorce or dissolution; financial orders; pre-marital agreements; procedure for financial orders; variation, collection, and enforcement of financial orders; protecting assets and the family home in financial order proceedings; separation and maintenance agreements; child support; pensions in financial proceedings; and taxation in family law.
Screening for mild cognitive impairment among older Albanian patients by clinical pharmacists
Authors: Harasani Klejda , Xhafaj Delina , Lekaj Adrisa , Veshi Livia , Olvera-Porcel Maria del Carmen
Published: January 2021

Objectives

To assess the prevalence of mild cognitive impairment (MCI) and its correlated factors among elderly Albanian patients using different screening tools applied by clinical pharmacists.

Methods

Patients aged 60 years old or more from two primary care centers located in two Albanian cities were included in the study. Two clinical pharmacists applied the MoCA/MoCA B (Montreal Cognitive Assessment/Basic) and the Mini-Cog in Albanian. A predictive multivariate logistic regression analysis and Kappa statistic were conducted.

Key findings

The prevalence of MCI using MoCA/MoCA B and Mini-Cog scales was 75.73 and 20.39%, respectively. There was a poor degree of agreement between them (Kappa 2.38). Older men had an increased risk of MCI.

Conclusions

The involvement of clinical pharmacists in screening for MCI might help in selecting vulnerable individuals for more specialized examination. The MoCA/MoCA B tool is recommended for higher sensitivity.
Numerical homogenization for nonlinear strongly monotone problems
Authors: Verfürth Barbara
Published: January 2021

In this work we introduce and analyse a new multiscale method for strongly nonlinear monotone equations in the spirit of the localized orthogonal decomposition. A problem-adapted multiscale space is constructed by solving linear local fine-scale problems, which is then used in a generalized finite element method. The linearity of the fine-scale problems allows their localization and, moreover, makes the method very efficient to use. The new method gives optimal a priori error estimates up to linearization errors. The results neither require structural assumptions on the coefficient such as periodicity or scale separation nor higher regularity of the solution. The effect of different linearization strategies is discussed in theory and practice. Several numerical examples including the stationary Richards equation confirm the theory and underline the applicability of the method.
Nature Identification of Chinese Herbal Medicine Compounds Based on Molecular Descriptors
Authors: Wei Guohui , Fu Xianjun , Wang Zhenguo
Published: January 2021

Background

The nature of Chinese herbal medicines (CHMs) is a bridge between traditional Chinese medicine and clinical application. Accurate nature identification of CHMs is essential for guiding the clinical application of CHMs.

Objective

To develop a new method for nature identification of CHMs according to compounds in CHMs.

Methods

The nature of a CHM is a comprehensive manifestation of the properties of various compounds in the CHM. In this study, 2012 CHM compounds were extracted to construct a compound data set. Molecular descriptors were utilized to build an identification model for classification of the cold-hot-neutral nature of CHM compounds.

Results

The predictive accuracy and confusion matrix were validated using the assembled data set. The best model produced accuracies of 96.5 ± 0.5% and 86.5 ± 1.5% on training set and test set, respectively. Furthermore, the identification model is robust in predicting the cold-hot-neutral nature of CHM compounds.

Conclusion

This work shows how a classification model for medical nature identification can be developed. The derived model can be utilized for the application of CHMs.

Highlights

To construct a nature identification model for analysis of the cold-hot-neutral nature of CHMs according to the compounds in CHMs.
Digital Retaliation? Denial-of-Service Attacks after Sanction Events
Authors: Lutscher Philipp M
Published: January 2021

Conventional wisdom expects to see a rise in cyber activities around aggressive foreign policy events. In this article, I test this claim by investigating whether sanctions lead to an increase in denial-of-service (DoS) attacks using new data on DoS attacks measured from Internet traffic. Exploring the development of DoS attacks around sanctions imposed against Russia in 2014 indeed shows an increase of DoS attacks against several sanction sender states. Extending this case study to a systematic analysis, including all sanction threats and impositions made by the United States and the European Union between 2008 and 2016, shows no apparent patterns. When I exclusively consider sanctions against technologically advanced countries, however, the frequency of attacks rises systematically against the United States. It thus appears that states do not always have to expect a digital retaliation after aggressive foreign policies. Nevertheless, sanctioning countries may have to anticipate an increase in DoS attacks when their governments impose sanctions against technologically advanced countries.
Perforation of the descending colon diverticulum in a patient following recovery from severe COVID-19 pneumonia: a case report
Authors: Hamaoka Michinori , Shiozaki Shohei , Nakahara Hideki , Itamoto Toshiyuki
Published: January 2021

The outcome of surgery in patients who have recovered from severe coronavirus disease 2019 (COVID-19) is unknown. Herein, we present a case of an emergency operation for acute pan-peritonitis due to perforation of the descending colon diverticulum in a patient who recovered from severe COVID-19 pneumonia. A 59-year-old man, who had recovered from severe COVID-19 pneumonia ~6 months previously, developed acute pan-peritonitis due to perforation of a diverticulum in the descending colon. Emergency surgery was performed, and the perforation was sutured and closed. He was discharged from the hospital 13 days postoperatively. There was no relapse of COVID-19 during the perioperative period of peritonitis surgery. General perioperative management may, therefore, be sufficient in patients who have recovered from COVID-19.
Isolation and characterization of the new SARS-CoV-2 variant in travellers from the United Kingdom to India: VUI-202012/01 of the B.1.1.7 lineage
Authors: Yadav Pragya D , Nyayanit Dimpal A , Sahay Rima R , Sarkale Prasad , Pethani Jayshri , Patil Savita , Baradkar Shreekant , Potdar Varsha , Patil Deepak Y
Published: January 2021

We have isolated the new severe acute respiratory syndrome coronavirus-2 variant of concern 202 012/01 from the positive coronavirus disease 2019 cases that travelled from the UK to India in the month of December 2020. This emphasizes the need for the strengthened surveillance system to limit the local transmission of this new variant.
Black holes LIGO/Virgo domination and single-lined binaries with a black hole candidate component
Authors: Lipunov Vladimir , Gorbovskoy Evgeny , Grinshpun Valeria , Vlasenko Daniil
Published: January 2021

In this letter, we note that the observed in the LIGO/Virgo experiment ratio of the detection rate of black holes to the rate of detection of binary neutron stars requires the assumption of a ‘conservative’ collapse of massive stars into a black hole: almost all the mass of the collapsing star goes under the horizon. This is consistent with the large masses of black holes detected by LIGO/Virgo. On the other hand, the assumption of a small loss of matter during the collapse into a black hole is in good agreement with the small eccentricity of single-lined binaries. At the same time, the absence of X-rays from most black holes in binary systems with blue stars is explained. We argue that three sets of LIGO/Virgo observations and data on the single-lined binary with a candidate black hole component confirm the scenario of the evolution of massive field binaries.
Using Mars co-orbitals to estimate the importance of rotation-induced YORP break-up events in Earth co-orbital space
Authors: de la Fuente Marcos C , de la Fuente Marcos R
Published: January 2021

Both Earth and Mars host populations of co-orbital minor bodies. A large number of present-day Mars co-orbitals is probably associated with the fission of the parent body of Mars Trojan 5261 Eureka (1990 MB) during a rotation-induced Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) break-up event. Here, we use the statistical distributions of the Tisserand parameter and the relative mean longitude of Mars co-orbitals with eccentricity below 0.2 to estimate the importance of rotation-induced YORP break-up events in Martian co-orbital space. Machine-learning techniques (k-means++ and agglomerative hierarchical clustering algorithms) are applied to assess our findings. Our statistical analysis identified three new Mars Trojans: 2009 SE, 2018 EC4, and 2018 FC4. Two of them, 2018 EC4 and 2018 FC4, are probably linked to Eureka but we argue that 2009 SE may have been captured, so it is not related to Eureka. We also suggest that 2020 VT1, a recent discovery, is a transient Martian co-orbital of the horseshoe type. When applied to Earth co-orbital candidates with eccentricity below 0.2, our approach led us to identify some clustering, perhaps linked to fission events. The cluster with most members could be associated with Earth quasi-satellite 469219 Kamo‘oalewa (2016 HO3) that is a fast rotator. Our statistical analysis identified two new Earth co-orbitals: 2020 PN1, which follows a horseshoe path, and 2020 PP1, a quasi-satellite that is dynamically similar to Kamo‘oalewa. For both Mars and Earth co-orbitals, we found pairs of objects whose values of the Tisserand parameter differ by very small amounts, perhaps hinting at recent disruption events. Clustering algorithms and numerical simulations both suggest that 2020 KZ2 and Kamo‘oalewa could be related.
Weighing Milky Way satellites with LISA
Authors: Korol Valeriya , Belokurov Vasily , Moore Christopher J , Toonen Silvia
Published: January 2021

White dwarf stars are a well-established tool for studying Galactic stellar populations. Two white dwarfs in a tight binary system offer us an additional messenger – gravitational waves – for exploring the Milky Way and its immediate surroundings. Gravitational waves produced by double white dwarf (DWD) binaries can be detected by the future Laser Interferometer Space Antenna (LISA). Numerous and widespread DWDs have the potential to probe shapes, masses, and formation histories of the stellar populations in the Galactic neighbourhood. In this work we outline a method for estimating the total stellar mass of Milky Way satellite galaxies based on the number of DWDs detected by LISA. To constrain the mass we perform a Bayesian inference using binary population synthesis models and considering the number of detected DWDs associated with the satellite and the measured distance to the satellite as the only inputs. Based on a fiducial binary population synthesis model we find that for large satellites the stellar masses can be recovered to within (1) a factor 2 if the star formation history (SFH) is known and (2) an order of magnitude when marginalizing over different SFH models. For smaller satellites we can place upper limits on their stellar mass. Gravitational wave observations can provide mass measurements for large satellites that are comparable, and in some cases more precise, than standard electromagnetic observations.
Invasive growth associated with cold-inducible RNA-binding protein expression drives recurrence of surgically resected brain metastases
Authors: Dankner Matthew , Caron Maxime , Al-Saadi Tariq , Yu WenQing , Ouellet Véronique , Ezzeddine Rima , Maritan Sarah M , Annis Matthew G , Le Phuong Uyen , Nadaf Javad , Neubarth Noah S , Savage Paul , Zuo Dongmei , Couturier Charles P , Monlong Jean , Djambazian Haig , Altoukhi Huda , Bourque Guillaume , Ragoussis Jiannis , Diaz Roberto J , Park Morag , Guiot Marie-Christine , Lam Stephanie , Petrecca Kevin , Siegel Peter M
Published: January 2021

Background

Sixty percent of surgically resected brain metastases (BrM) recur within 1 year. These recurrences have long been thought to result from the dispersion of cancer cells during surgery. We tested the alternative hypothesis that invasion of cancer cells into the adjacent brain plays a significant role in local recurrence and shortened overall survival.

Methods

We determined the invasion pattern of 164 surgically resected BrM and correlated with local recurrence and overall survival. We performed single-cell RNA sequencing (scRNAseq) of >15,000 cells from BrM and adjacent brain tissue. Validation of targets was performed with a novel cohort of BrM patient-derived xenografts (PDX) and patient tissues.

Results

We demonstrate that invasion of metastatic cancer cells into the adjacent brain is associated with local recurrence and shortened overall survival. scRNAseq of paired tumor and adjacent brain samples confirmed the existence of invasive cancer cells in the tumor-adjacent brain. Analysis of these cells identified cold-inducible RNA-binding protein (CIRBP) overexpression in invasive cancer cells compared to cancer cells located within the metastases. Applying PDX models that recapitulate the invasion pattern observed in patients, we show that CIRBP is overexpressed in highly invasive BrM and is required for efficient invasive growth in the brain.

Conclusions

These data demonstrate peritumoral invasion as a driver of treatment failure in BrM that is functionally mediated by CIRBP. These findings improve our understanding of the biology underlying postoperative treatment failure and lay the groundwork for rational clinical trial development based upon invasion pattern in surgically resected BrM.
PARP-mediated PARylation of MGMT is critical to promote repair of temozolomide-induced O6-methylguanine DNA damage in glioblastoma
Authors: Wu Shaofang , Li Xiaolong , Gao Feng , de Groot John F , Koul Dimpy , Yung W K Alfred
Published: January 2021

Background

Temozolomide (TMZ) resistance in glioblastoma multiforme (GBM) is mediated by the DNA repair protein O6-methylguanine DNA methyltransferase (MGMT). MGMT promoter methylation (occurs in about 40% of patients) is associated with loss of MGMT expression (MGMT−) that compromises DNA repair, leading to a favorable response to TMZ therapy. The 60% of patients with unmethylated MGMT (MGMT+) GBM experience resistance to TMZ; in these patients, understanding the mechanism of MGMT-mediated repair and modulating MGMT activity may lead to enhanced TMZ activity. Here, we report a novel mode of regulation of MGMT protein activity by poly(ADP-ribose) polymerase (PARP).

Methods

MGMT-PARP interaction was detected by co-immunoprecipitation. PARylation of MGMT and PARP was detected by co-immunoprecipitation with anti-PAR antibody. O6-methylguanine (O6-MetG) adducts were quantified by immunofluorescence assay. In vivo studies were conducted in mice to determine the effectiveness of PARP inhibition in sensitizing GBM to TMZ.

Results

We demonstrated that PARP physically binds with MGMT and PARylates MGMT in response to TMZ treatment. In addition, PARylation of MGMT by PARP is required for MGMT binding to chromatin to enhance the removal of O6-MetG adducts from DNA after TMZ treatment. PARP inhibitors reduced PARP-MGMT binding and MGMT PARylation, silencing MGMT activity to repair O6-MetG. PARP inhibition restored TMZ sensitivity in vivo in MGMT-expressing GBM.

Conclusion

This study demonstrated that PARylation of MGMT by PARP is critical for repairing TMZ-induced O6-MetG, and inhibition of PARylation by PARP inhibitor reduces MGMT function rendering sensitization to TMZ, providing a rationale for combining PARP inhibitors to sensitize TMZ in MGMT-unmethylated GBM.