bluuebunny/crossref_metadata_2025 huggingface dataset:
SELECTION FOR LINKAGE MODIFICATION II. A RECOMBINATION BALANCE FOR NEUTRAL MODIFIERS
Authors: Feldman Marcus W , Balkau Beverley
Published: January 2021

A stable polymorphic equilibrium may be established at a selectively-neutral gene locus which controls the extent of recombination between two other selected loci. The condition for the existence of the stable polymorphism is analogous to heterozygous advantage. The heterozygote at the modifying locus should produce a recombination fraction allowing the greatest linkage disequilibrium. In the models treated this has the effect of producing the highest mean fitness. The relationship of these findings to general problems of coadaptation is discussed.
THE LAMBDA F MUTANTS BELONG TO TWO CISTRONS
Authors: Boklage Charles E , Wong Emery Chun-Te , Bode Vernon C
Published: January 2021

Amber mutants previously mapped at seven sites in head gene F exhibit two contrasting phenotypes. Mutant F423, located in the right half of gene F, makes defective head particles with normal size λDNA. These particles are complemented by crude lysates of mutants in other head genes. Mutants F785, F471 and F730 map in three adjacent sites in the left half of gene F. They are not complemented by lysates of other head mutants and do not produce headlike particles. Their lysates complement the incomplete heads present in F423. In vivo all three mutants are complemented by F423 but not by each other.
AN EXPERIMENTAL COMPARISON OF INDIVIDUAL, FAMILY AND COMBINATION SELECTION
Authors: Wilson S P
Published: January 2021

Two selection experiments comparing the relative efficiencies of individual, family, and combination selection were conducted. The expected results for larval weight of Tribolium (h  2 = 0.20) and for pupal weight (h  2 = 0.40) were that combination selection would be a more efficient method than family selection, and that family selection would exceed individual selection. In experiment I, individual selection produced more response (P < 0.05) than did combination or family, which was not in agreement with expectation. There was confounding of inbreeding levels and random drift due to differential effective population sizes in the lines selected by different methods. Experiment II consisted of ten single-generation selection tests. An advantage of this approach is that it eleminates the inherent problems of differential inbreeding levels and differential rates of genetic drift due to unequal population sizes among the methods of selection. There were no statistically significant differences in efficiency among the three methods of selection for both traits. This was contrary to theoretical expectations but does suggest that with traits of 20% h2 or higher, and where feasible, one may be justified in basing selection decisions on the phenotype of the individual only. Other advantages of single generation testing are that it allows more precise testing of selection theory and unbiased standard errors for estimates of realized heritability.
COMPLEMENTATION ANALYSIS OF LATE LETHAL MUTANTS OF DROSOPHILA MELANOGASTER
Authors: Shearn Allen
Published: January 2021

Late larval and pupal lethal mutants of Drosophila define those gene functions which are essential for the development of pupae (metamorphosis) but not for embryonic or larval development. In a previous report the isolation of a large number of such mutants was outlined, and a description of the imaginal disc defects in those mutants was described. This report concerns genetic analysis of those mutants. 3746 different pairwise combinations of mutants have been tested for complementation. Only 10 pairs fail to complement. In all of the cases tested, the lethal mutation in each member of a non-complementing pair has a similar map location. In addition to the non-complementing pairs one group of seven partially-complementing mutants has been identified.

Comparisons of the imaginal disc defects within the non-complementing pairs and the lethal hybrids formed by the respective pairs were made to test for uniformity of phenotype. No significant qualitative differences were detected between any non-complementing pairs or their respective hybrids.
RECIPROCAL RECURRENT SELECTION COMPARED TO WITHIN-STRAIN SELECTION FOR INCREASING RATE OF EGG LAY OF TRIBOLIUM UNDER OPTIMAL AND STRESS CONDITIONS
Authors: Orozco Fernando , Bell A E
Published: January 2021

A replicated comparison of reciprocal recurrent selection (rrs) based on crossbred performance and within strain-selection (wss) based on purebred performance was made in three diverse environments over ten generations for the improvement of a heterotic trait, 4-day virgin egg lay of Tribolium castaneum. A selection intensity of 20% based on performance in either an optimum (33°), a mild stress (38°), or a severe stress (28°) environment was applied uniformly. Periodically, the performance of each population was measured in all three environments to provide both direct and correlated responses.—Heritability of egg lay in the base population ranged from 0.36 ± 0.03 in optimum to 0.26 ± 0.03 in severe stress. Estimates of dominance effects assumed significant proportions in severe stress only. Genetic correlations for egg lay in diverse environments were large and positive (.6 to .8) .—Only in severe stress did the rrs response significantly exceed that for wss. Quadratic adjustments fitted t3 response curves revealed that small initial genetic gains under rrs were followed by significantly increasing rates of gain in late generations of selection. The reverse was true for wss. This and evidence from realized heritabilities and genetic correlations suggested that rrs had utilized both additive and dominance effects, but wss response was limited to additive effects.—These results agree with selection theory in demonstrating that purebred selection is mwe efficient than crossbred selection in utilizing additive gene effects. The latter method has merit when non-additive effects assume significant proportions, and this is the more probable case for severe stress conditions.
THE DNA OF CAENORHABDITIS ELEGANS
Authors: Sulston J E , Brenner S
Published: January 2021

Chemical analysis and a study of renaturation kinetics show that the nematode, Caenorhabditis elegans, has a haploid DNA content of 8 x IO7 base pairs (20 times the genome of E. coli). Eighty-three percent of the DNA sequences are unique. The mean base composition is 36% GC; a small component, containing the rRNA cistrons, has a base composition of 51% GC. The haploid genome contains about 300 genes for 4s RNA, 110 for 5s RNA, and 55 for (18 + 28)S RNA.
ENZYME VARIABILITY IN NATURAL POPULATIONS OF DAPHNIA MAGNA II. GENOTYPIC FREQUENCIES IN PERMANENT POPULATIONS
Authors: Hebert Paul D N
Published: January 2021

In permanent habitats populations of the cyclical parthenogen, Daphnia magna, reproduce by continued parthenogenesis and are subject to only sporadic sexual recruitment. The genetic effects of this breeding system have been investigated by analyzing allozyme frequencies in thirteen populations of D. magna—Genotypic frequencies at polymorphic loci characteristically deviated markedly from Hardy-Weinberg proportions and gametic phase imbalance between loci was frequent. Genotypic frequencies were subject to violent, selectively determined oscillations over short periods of time. These observations suggest that permanent populations of D. magna ordinarily consist of a limited number of highly structured genotypes. The adaptational advantages offered by such structuring may have been a major selective factor favoring the evolution of cyclical Parthenogenesis.
REC-MEDIATED RECOMBINATIONAL HOT SPOT ACTIVITY IN BACTERIOPHAGE LAMBDA II. A MUTATION WHICH CAUSES HOT SPOT ACTIVITY
Authors: Lam Stephen T , Stahl Mary M , McMilin Kenneth D , Stahl Franklin W
Published: January 2021

Crosses have been performed which identify phage mutants (chi) which cause recombinational hot spot activity in λ. The hot spot activity is found in crosses of red- gam- chi- strains in rec+ hosts; in the crosses reported here, both the chi- mutations and the hot spot are located near the right end of the chromosome. The hot spot occurs in standard crosses as well as under conditions which block DNA synthesis, and is dependent on a functional host recB gene.—The chi mutation is shown to be dominant, but the tests do not show whether chi is a gene or a site.
ANALYSIS OF GENES CONTROLLING F1 STERILITY IN RICE BY THE USE OF ISOGENIC LINES
Authors: Oka Hiko-Ichi
Published: January 2021

In order to look into the genetic basis of intervarietal F1 sterility in rice (Oryza sativa L.), a series of backcrosses (up to B13) was carried out using Taichung 65 (Japonica type) as the recurrent parent and several Indica varieties as donor parents. A number of "isogenic F1-sterile lines" were isolated by test-crossing fertile F2 plants obtained from the selfing of partly pollensterile backcross segregants. Crossing experiments with the isogenic lines confirmed the author's previous hypothesis that there are sets of duplicate gametic lethals (s genes) and that gametes carrying a double recessive combination (s1s2) of these deteriorate during development, though in the present hypothesis the genes are considered to affect the development of microspores only. Assuming that Taichung 65 has the genotype s1/s1 + 2/+2 and a donor parent (like an isogenic F1-sterile line derived from it) has +1/+1s2/s2, pollen grains with +1s2 have shown a higher fertilizing capacity in the genetic background of Taichung 65 than those with s1 +2, while those with +1 +2 have a lower fertilizing capacity. This certational advantage of alien genes was considered to be an internal mechanism that helped the development of F1 sterility relationships among rice varieties. The isogenic F1-sterile lines derived from different donor parents each had a set of s genes at different loci. Linkage relations were detected between the s loci and three gene markers.
ON THE STRUCTURE OF GENE CONTROL REGIONS
Authors: Wallace Bruce , Kass Thomas L
Published: January 2021

A model emphasizing the possible genetic role of tandem duplications of reverse repeats has been developed as an extension of Crick's (1971) general model for the chromosomes of higher organisms. Although developed initially (1) to explain why random differences in the control regions of individual gene loci might confer a selective advantage on heterozygous individuals as well as (2) to offer the species a means by which such differences might be effected without mutational harm, it seems that control regions built on a foundation of tandemly duplicated reverse repeats would exhibit many properties previously observed in studies on mutable loci in various organisms.
A NOTE ON THE BALANCE BETWEEN RANDOM SAMPLING AND POPULATION SIZE (ON THE 30TH ANNIVERSARY OF G. MALÉCOT'S PAPER)
Authors: Seneta E
Published: January 2021

Wright's model for the effects of random fluctuations in gene frequency in a population of fixed size is generalized to randomly fluctuating population size, and treated from the viewpoint of G. Malécot, using a martingale convergence theorem. The gene frequency approaches a limit, whose value depends on the actual realization, or history, of the process; that is, convergence is with probability one (or: almost surely) in statistical language. The limit does not necessarily represent a state of fixation of either allele; in particular, the limiting probability distribution is not necessarily trivial. For the special case of deterministically varying population size, a necessary and sufficient condition for such non-triviality is given.
ISOLATION AND PROPERTIES OF SELENOMETHIONINE-RESISTANT MUTANTS OF NEUROSPORA CRASSA
Authors: Chen Gregory S , Metzenberg Robert L
Published: January 2021

Mutants resistant to selenomethionine were isolated, and their properties studied. Mapping studies indicate that the mutation sites are located near the eth-1r locus in linkage group I, about ten map units away from the mating type locus. The sites of new mutation are either allelic to or very close to eth-1r. They are resistant not only to selenomethionine but also to ethionine, while the ethionine-resistant mutant, eth-1r, is sensitive to selenomethionine. The selenomethionine-resistant mutants are also temperature-sensitive mutants. However, they can grow at higher temperatures in medium containing 1 M glycerol.—It is very unlikely that the resistance is due to a change in the permeability of the membrane. Aryl sulfatase of se-metr mutants is not repressed by a high concentration of methionine (5 mM), although inorganic sulfate (2 mM) still can cause total repression. The γ-cystathionase levels of the mutants are normal, but the S-adenosylmethionine synthetase levels are only one-tenth of that observed in the wild-type strain. The heat-stability of this enzyme in the mutant is also different from that of the wild-type enzyme suggesting that the mutation might affect the structural gene of S-adenosylmethionine synthetase.
GENETIC ANALYSIS OF MUTATIONS AFFECTING GROWTH OF SACCHAROMYCES CEREVISIAE AT LOW TEMPERATURE
Authors: Singh Arjun , Manney T R
Published: January 2021

A large number of genes control growth of the yeast Saccharomyces cerevisiae at low temperatures (< 10°). Approximately 47 percent of the mutants selected for inability to grow at 4-5°C show increased sensitivity to cycloheximide. In 3 of 4 cases tested, supersensitivity to cycloheximide and inability to grow at the low temperature segregate together and thus appear to be effects of the same mutation. Since many cold-sensitive mutants of bacteria have been found to have altered ribosomes and since cycloheximide resistance in yeast can be caused by ribosomal changes, this suggests that the mutants having low-temperature-sensitive growth may be defective in ribosome-assembly processes at the low temperatures. Two of the lts loci, lts1 and lts3 have been located on chromosome VII and another two, lts4 and lts10 on chromosome IV. A mutation, cyh10, conferring cycloheximide resistance, but not cold sensitivity, has been located close to the centromere on chromosome II.
GENE DIFFERENCES BETWEEN THE SEX RATIO AND STANDARD GENE ARRANGEMENTS OF THE X CHROMOSOME AND LINKAGE DISEQUILIBRIUM BETWEEN LOCI IN THE STANDARD GENE ARRANGEMENT OF THE X CHROMOSOME IN DROSOPHILA PSEUDOOBSCURA
Authors: Prakash Satya
Published: January 2021

The Standard and Sex Ratio gene arrangements of the X chromosome of D. pseudobscura differ from each other in allele frequencies at the four X chromosome loci, esterase-5, adult acid phosphatase-6, phosphoglucomutase-1 and octanol dehydrogenase-3. The Standard arrangement which is the common arrangement in all populations is polymorphic at these loci in varying degrees, the geographically less widespread Sex Ratio arrangement has little polymorphism and is genically predominantly E-51.04 AP-6- Pgm11.0 ODH-31.0. The Sex Ratio arrangement from different populations is alike at all of the four loci, the Standard arrangement shows some gene frequency differences among populations. The Standard and Sex Ratio arrangements differ from each other by three inversions which suggests that the two arrangements are "old". Gene differences between these two chromosome arrangements can be explained due to differential natural selection of alleles in the Standard and Sex Ratio arrangments.—The order and percent recombination among these four loci in the Standard arrangement are: E-5—.294—AP-6—.335—Pgm-1—.024—ODH-3. The Standard X chromosomes from four different wild populations were analyzed for evidence of linkage disequilibrium between pairs of loci at these four loci. No evidence of linkage disequilibrium between pairs of loci was obtained. However, when linkages involving simultaneously three loci, E-5, AP-6 and Pgm-1 are considered, then significant departure from linkage equilibrium is observed.
SEGREGATION AND RECOMBINATION OF NON-MENDELIAN GENES IN CHLAMYDOMONAS
Authors: Gillham Nicholas W , Boynton John E , Lee Robert W
Published: January 2021

Non-Mendelian genes in Chamydomonas reinhardtii are inherited in a uniparental (UP) fashion. Most zygotes and their progeny receive UP genes only from the mt  + or maternal parent. However, a few exceptional zygotes are also found in which the mt  - or paternal UP genome is transmitted. Most of the exceptional zygotes are biparental in that their progeny segregate UP genes transmitted by both parents. As a result, biparental zygotes have been extensively used to study the rules governing UP inheritance.

The frequency of biparental zygotes can be greatly increased if the maternal parent is irradiated with ultraviolet light prior to mating. Based principally on studies with ultraviolet-induced biparental zygotes, Sager has argued that a vegetative cell contains two copies of the UP genome and that the progeny of a biparental zygote receive a copy derived from each parent. Results reported in this paper with spontaneous and ultraviolet-induced biparental zygotes do not support the two copy model, but argue for a mulitple copy model with most of the copies normally being transmitted by the maternal parent. A multiple copy model which accounts for both Sager's results and ours is presented.
TRIPSACUM-MAIZE INTERACTION: A NOVEL CYTOGENETIC SYSTEM
Authors: de Wet J M J , Harlan J R
Published: January 2021

The genera Zea and Tripsacum cross readily when they are not isolated by gametophytic barriers, and it has been postulated that intergeneric introgression played a role in the evolution of maize. The basic x = 9 Tripsacum and x = 10 Zea genomes have little cytological affinity for each other in hybrids that combine 10 Zea with 18 Tripsacum chromosomes. However, one to four Tripsacum chromosomes sometimes associate with Zea chromosomes in hybrids between Z. mays (2n = 20) and T. dactyloides (2n = 72). These hybrids with 10 Zea and 36 Tripsacum chromosomes frequently produce functional female gametes with 36 Tripsacum chromosomes only. When they are pollinated with maize, their offspring again have 36 Tripsacum and 10 maize chromosomes, but the Tripsacum genome is contaminated with maize genetic material. In these individuals, intergenome pairing is the rule, and when they are pollinated with maize, their offspring have 36 Tripsacum and 10, 12, 14, 16, 18, or 20 Zea chromosomes. Plants with 36 Tripsacum and 20 Zea chromosomes behave cytologically as alloploids, although the Tripsacum genome is contimated with maize, and one basic maize genome is contaminated with with Tripsacum genetic material. When they are pollinated with maize, offspring with 18 Tripsacum and 20 Zea chromosome are obtained. Further successive backcrosses with maize selectively eliminate Tripsacum chromosomes, and eventually plants with 2n = 20 Zea chromosomes are recovered. Many of these maize plants are highly "tripsacoid." Strong gametophytic selection for essentially pure Zea gametes, however, eliminates all obvious traces of Tripsacum morphology within a relatively few generations.
THE ROLE OF BREEDING AND GENETICS IN ANIMAL PRODUCTION IMPROVEMENT IN THE DEVELOPING COUNTRIES
Authors: Rendel Jan
Published: January 2021

Availability of animal protein for human consumption is very low in the developing countries mainly because of low productivity of existing livestock; ways and means to improve productivity through breeding are discussed and some basic issues requiring further research pointed out.
VARIATION OF MUTAGENIC ACTION ON NONSENSE MUTANTS AT DIFFERENT SITES IN THE ISO-1-CYTOCHROME c GENE OF YEAST
Authors: Sherman Fred , Stewart John W
Published: January 2021

Three ochre and two amber mutants in yeast have been definitively identified by the amino acid replacements in iso-1-cytochromes c from intragenic revertants. Except for rare and sometimes unusual changes, all of the replacements were single amino acids whose codons differed from UAA or UAG by one base. These assignments, which were based on the absence of tryptophan replacements in ochre revertants, could be corroborated from the studies of two groups of suppressors that were shown to act on either the ochre or amber mutants. All five nonsense mutants are located at different sites in the cyc1 gene and all are at sites that can be occupied by amino acids having a wide range of structures. The relative frequencies of the amino acid replacements indicate that identical codons located at different sites may respond differently to a mutagenic agent. Notably glutamine replacements occurred almost exclusively in UV-induced revertants of only one ochre mutant cyc1-9, but not at all or at reduced proportions in the others. Similarly, lysine replacements occurred almost exclusively in the NA-induced revertants of only the ochre mutant cyc1-72, but not at all in the others. These and other results reveal that mutation of A·T base pairs by UV and nitrous acid are dependent upon the location of the codon within the gene as well as the location of the base pair within the codon. From these findings, it appears as if the type of base-pair changes induced by UV and nitrous acid are strongly influenced by adjacent nucleotide sequences.
Efficient multiscale imaging of subsurface resistivity with uncertainty quantification using ensemble Kalman inversion
Authors: Tso Chak-Hau Michael , Iglesias Marco , Wilkinson Paul , Kuras Oliver , Chambers Jonathan , Binley Andrew
Published: January 2021

Electrical resistivity tomography (ERT) is widely used to image the Earth’s subsurface and has proven to be an extremely useful tool in application to hydrological problems. Conventional smoothness-constrained inversion of ERT data is efficient and robust, and consequently very popular. However, it does not resolve well sharp interfaces of a resistivity field and tends to reduce and smooth resistivity variations. These issues can be problematic in a range of hydrological or near-surface studies, for example mapping regolith-bedrock interfaces. While fully Bayesian approaches, such as those using Markov chain Monte Carlo sampling, can address the above issues, their very high computation cost makes them impractical for many applications. Ensemble Kalman inversion (EKI) offers a computationally efficient alternative by approximating the Bayesian posterior distribution in a derivative-free manner, which means only a relatively small number of ‘black-box’ model runs are required. Although common limitations for ensemble Kalman filter-type methods apply to EKI, it is both efficient and generally captures uncertainty patterns correctly. We propose the use of a new EKI-based framework for ERT which estimates a resistivity model and its uncertainty at a modest computational cost. Our EKI framework uses a level-set parametrization of the unknown resistivity to allow efficient estimation of discontinuous resistivity fields. Instead of estimating level-set parameters directly, we introduce a second step to characterize the spatial variability of the resistivity field and infer length scale hyperparameters directly. We demonstrate these features by applying the method to a series of synthetic and field examples. We also benchmark our results by comparing them to those obtained from standard smoothness-constrained inversion. Resultant resistivity images from EKI successfully capture arbitrarily shaped interfaces between resistivity zones and the inverted resistivities are close to the true values in synthetic cases. We highlight its readiness and applicability to similar problems in geophysics.
Mutations causing Lopes-Maciel-Rodan syndrome are huntingtin hypomorphs
Authors: Jung Roy , Lee Yejin , Barker Douglas , Correia Kevin , Shin Baehyun , Loupe Jacob , Collins Ryan L , Lucente Diane , Ruliera Jayla , Gillis Tammy , Mysore Jayalakshmi S , Rodan Lance , Picker Jonathan , Lee Jong-Min , Howland David , Lee Ramee , Kwak Seung , MacDonald Marcy E , Gusella James F , Seong Ihn Sik
Published: January 2021

Huntington’s disease pathogenesis involves a genetic gain-of-function toxicity mechanism triggered by the expanded HTT CAG repeat. Current therapeutic efforts aim to suppress expression of total or mutant huntingtin, though the relationship of huntingtin’s normal activities to the gain-of-function mechanism and what the effects of huntingtin-lowering might be are unclear. Here, we have re-investigated a rare family segregating two presumed HTT loss-of-function (LoF) variants associated with the developmental disorder, Lopes-Maciel-Rodan syndrome (LOMARS), using whole-genome sequencing of DNA from cell lines, in conjunction with analysis of mRNA and protein expression. Our findings correct the muddled annotation of these HTT variants, reaffirm they are the genetic cause of the LOMARS phenotype and demonstrate that each variant is a huntingtin hypomorphic mutation. The NM_002111.8: c.4469+1G>A splice donor variant results in aberrant (exon 34) splicing and severely reduced mRNA, whereas, surprisingly, the NM_002111.8: c.8157T>A NP_002102.4: Phe2719Leu missense variant results in abnormally rapid turnover of the Leu2719 huntingtin protein. Thus, although rare and subject to an as yet unknown LoF intolerance at the population level, bona fide HTT LoF variants can be transmitted by normal individuals leading to severe consequences in compound heterozygotes due to huntingtin deficiency.
Structure and ancestry patterns of Ethiopians in genome-wide autosomal DNA
Authors: Hellenthal Garrett , Bird Nancy , Morris Sam
Published: January 2021

We review some of the current insights derived from the analyses of new large-scale, genome-wide autosomal variation data studies incorporating Ethiopians. Consistent with their substantial degree of cultural and linguistic diversity, genetic diversity among Ethiopians is higher than that seen across much larger geographic regions worldwide. This genetic variation is associated in part with ethnic identity, geography and linguistic classification. Numerous and varied admixture events have been inferred in Ethiopian groups, for example, involving sources related to present-day groups in West Eurasia and North Africa, with inferred dates spanning a few hundred to more than 4500 years ago. These disparate inferred ancestry patterns are correlated in part with groups’ broad linguistic classifications, though with some notable exceptions. While deciphering these complex genetic signals remains challenging with available data, these studies and other projects focused on resolving competing hypotheses on the origins of specific ethnolinguistic groups demonstrate how genetic analyses can complement findings from anthropological and linguistic studies on Ethiopians.
Analysing endometrial microbiome: methodological considerations and recommendations for good practice
Authors: Molina Nerea M , Sola-Leyva Alberto , Haahr Thor , Aghajanova Lusine , Laudanski Piotr , Castilla Jose Antonio , Altmäe Signe
Published: January 2021

There is growing evidence that the upper female genital tract is not sterile, harbouring its own microbial communities. However, the significance and the potential effect of endometrial microorganisms on reproductive functions remain to be fully elucidated. Analysing the endometrial microbiome, the microbes and their genetic material present in the endometrium, is an emerging area of study. The initial studies suggest it is associated with poor reproductive outcomes and with different gynaecological pathologies. Nevertheless, studying a low-biomass microbial niche as is endometrium, the challenge is to conduct well-designed and well-controlled experiments in order to avoid and adjust for the risk of contamination, especially from the lower genital tract. Herein, we aim to highlight methodological considerations and propose good practice recommendations for future endometrial microbiome studies.
Maternal use of hormonal contraception and epilepsy in offspring
Authors: Halane H I M , Hargreave M , Kjaer S K , Christensen J , Mørch L S
Published: January 2021

STUDY QUESTION

Is maternal use of hormonal contraception associated with the development of epilepsy in the offspring?

SUMMARY ANSWER

We found that maternal use of hormonal contraception was associated with a slightly increased risk of epilepsy in the offspring.

WHAT IS KNOWN ALREADY

Foetal exposure to exogenous hormones has been associated with changes in brain development. However, little is known about maternal hormonal contraception use and development of epilepsy in the offspring.

STUDY DESIGN, SIZE, DURATION

A nationwide cohort of all live born children born in Denmark between 1 January 1998 and 31 December 2014, was followed from day 29 after birth for epilepsy (first diagnosis of epilepsy or first redeemed prescription for anti-epileptic medication) to censoring (emigration, death) or 31 December 2015, whichever occurred first.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Diagnoses of epilepsy were obtained from the National Patient Registry. The Danish National Prescription Registry supplied information on redeemed prescriptions for hormonal contraception and anti-epileptic medication. Maternal hormonal contraception use was categorized as never use (reference group), previous use (prescriptions redeemed >3 months before pregnancy start) and recent use (prescriptions redeemed ≤3 months before or during pregnancy).

MAIN RESULTS AND THE ROLE OF CHANCE

The data show that 17 585 children developed epilepsy during a median follow-up of 9.2 years (9 732 635 person–years). The hazard ratio (HR) for epilepsy was 1.07 (95% CI 1.02–1.13) in children of mothers who had used any type of hormonal contraception recently, compared with children of mothers who had not used hormonal contraception. The HR was similar for recent use of oral combined products, while the HRs for recent or previous use of non-oral combined products were 1.32 (95% CI 0.98–1.77) and 1.16 (95% CI 1.02–1.32), respectively. For non-oral progestin-only products, the HRs were 1.19 (95% CI 1.04–1.38) and 1.53 (95% CI 1.31–1.80), respectively, for recent and previous use.

LIMITATIONS, REASONS FOR CAUTION

There may be some misclassification of maternal hormonal contraception use, as some women may not have used the redeemed prescriptions or used them at a different point in time; potentially leading to an attenuation of the estimates. In addition, although we were able to account for known risk factors for epilepsy, unknown or residual confounding cannot be ruled out.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings are based on nationwide population-based data and can therefore be applied to other similar populations. However, as this is the first study in this field, further studies are needed to confirm our findings.

STUDY FUNDING/COMPETING INTEREST(S)

No specific funding was obtained for this study, which was supported by internal funding at the Unit of Virus, Lifestyle and Genes. All authors report no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.
Assessing impacts of environmental peacebuilding in Caquetá, Colombia: a multistakeholder perspective
Authors: Morales-Muñoz Héctor , Löhr Katharina , Bonatti Michelle , Eufemia Luca , Sieber Stefan
Published: January 2021

A major challenge in the field of environmental peacebuilding is showing the impact of its initiatives. Questions emerge, such as what kind of postwar peacebuilding dimensions are more likely to be affected by natural resource management projects? Although quantitative studies assess the relation between natural resource management programmes and conflict, the question remains: what are the mechanisms involved in implementing projects designed for environmental peacebuilding? To answer these questions, a mixed methods research approach is chosen, combining four qualitative and quantitative methods to triangulate results. First, we identify a set of peacebuilding dimensions and mechanisms based in the literature that facilitate assessing the impact of sustainable land-use systems (SLUS) design in the post-peace agreement region of Caquetá, Colombia. Second, not only do we interview experts and practitioners at global, national (Colombia) and local (Department of Caquetá) levels in the fields of peacebuilding, natural resource management and environmental peacebuilding, we also conduct three workshops and a survey in Caquetá to prioritize dimensions and discover explanatory mechanisms. The case of Caquetá, Colombia, shows that peacebuilding dimensions, such as socio-economic inclusion (e.g. sustainable livelihoods), creation of governance scenarios, and building capacities for dialogue and a peace culture, should be addressed to take account of the impacts of SLUS projects in post-conflict peacebuilding.
Sources of inflation and the effects of balanced budgets and inflation targeting in developing economies
Authors: Martins Guilherme Klein , Skott Peter
Published: January 2021

This article presents a model in which distributional conflict and cross-sectoral interactions between demand and supply side forces determine inflation in developing countries. We show that the standard macroeconomic policy recommendations of inflation targeting and balanced budgets (i) increase volatility by amplifying external shocks and (ii) can lead to premature deindustrialization. The recent Brazilian experience is used to illustrate the argument.
Incidence and Impact of Parvovirus B19 Infection in Seronegative Solid Organ Transplant Recipients
Authors: Rezahosseini Omid , Ekenberg Christina , Møller Dina Leth , Sørensen Søren Schwartz , Wareham Neval Ete , Perch Michael , Gustafsson Finn , Rasmussen Allan , Kirkby Nikolai , Reekie Joanne , Lundgren Jens , Nielsen Susanne Dam
Published: January 2021

Routine monitoring of parvovirus B19 (B19V) the first 6 months posttransplantation was performed in 241 seronegative solid organ transplant (SOT) recipients. Incidence rates during the first month and the second to sixth months posttransplantation were 1.2 (95% confidence interval [CI], .33–3.2) and 0.21 (95% CI, .06–.57) per 100 recipients per month, respectively. Of the 6 SOT recipients with positive B19V polymerase chain reaction, 3 (50%) were admitted to hospital and 2 (33%) were treated with intravenous immunoglobulin. Thus, routine monitoring of B19V in seronegative SOT recipients may not be necessary. Targeted screening 1 month posttransplantation and screening upon clinical suspicion could be an alternative strategy.
Migrants as Engines of Financial Globalization: The Case of Global Banking
Authors: Zeitz Alexandra O , Leblang David A
Published: January 2021

Does international migration contribute to the spread of global commerce? Recent work demonstrates the relevance of international migration for patterns of investment, focusing on migrants’ role in facilitating investment from their host country to their country of origin. By contrast, we investigate the potential for migrants to attract inward investment into their host country. As customers, migrants shape the composition of the market in the country where they live, such that global networks of migrants can shape investment decisions of co-national firms. Focusing on a single sector, banking, we identify the mechanisms by which international migration attracts foreign investment. First, migrants may prefer home country banks, especially if they are excluded from financial services in their host country. Second, migrants require financial institutions to send remittances to their country of origin. We test these arguments using a global sample of foreign bank ownership data and find that bilateral migrant networks are a predictor of cross-border banking investment. These findings speak to how the composition of markets affects international investment, as well as the reinforcing relationship between two features of globalization: international migration and financial integration.
The Validation of the SIMUL-qPCR Top 7 STEC Assay Collection: AOAC Performance Tested MethodSM 022001
Authors: Lonczynski Thomas , Cowin Laura
Published: January 2021

Background

The Simultaneous Multiplex Real Time PCR (SIMUL-qPCR) Top 7 STEC Assay Collection is a quick, reliable method for detecting top seven Shiga toxin-producing Escherichia coli (STEC) in raw beef trim, raw ground beef, and beef carcass sampling sheets. Each assay multiplexes several targets in one run to identify E. coli O157: H7, O26, O45, O103, O111, O121, O145, Shiga toxin, and intimin genes. This collection uses specifically optimized proprietary media for single-step recovery and enrichment of enterohemorrhagic E. coli.

Objective

This report details the method validation study to validate raw beef trim, raw ground beef, and beef carcass sampling sheets.

Method

Matrix studies for raw beef trim, raw ground beef, and beef carcass sampling sheets, inclusivity/exclusivity, product consistency/stability, and robustness testing were conducted to assess the method’s performance.

Results

Fifty top seven STEC isolates were analyzed with the SIMUL-qPCR assay. Thirty-two isolates, including closely related non-E. coli species and E. coli non-STEC strains, were also tested. Inclusivity showed the collection detected the Shiga toxin (stx) gene, intimin (eae) gene, and top seven serogroups. None of the 32 exclusivity strains were detected. The candidate and reference methods’ results had no statistically significant differences during matrix studies. Small variations in critical test parameters (enrichment time, extraction reagent volume, and extracted sample volume) did not adversely affect the assay’s performance, and stability testing indicated consistent results for at least one year.

Conclusions

The data presented demonstrate that the SIMUL-qPCR Top 7 STEC Assay is a reliable method for detecting the top seven STEC.

Highlights

The Applied Food Diagnostics, Inc. Simultaneous Multiplex Real Time PCR (SIMUL-qPCR) Top 7 STEC Assay is capable of detecting the top seven Shiga toxin-producing Escherichia coli in beef trim, ground beef, and beef carcass sampling sheets in as little as 10 hours of enrichment.
Habitat associations of small mammal communities in a restored prairie system in southern Illinois
Authors: Glass Alex , Eichholz Michael W
Published: January 2021

Extensive habitat loss and degradation have transformed the grasslands of North America into one of the continent’s most vulnerable ecosystems and have greatly imperiled the plants and animals that depend on them. Small mammal communities play a pivotal role in maintaining the health and function of grasslands, and managing small mammal populations is an important, though overlooked, part of grassland restoration and management. We identified habitat variables in restored tallgrass prairie patches that were most strongly associated with variation in small mammal abundance and community composition, with the goal of aiding management efforts to manipulate small mammal populations. We found that small mammal abundance at the local vegetation scale was negatively related both to litter depth and plant diversity. At the landscape scale, small mammal abundance was positively associated with the amount of water surrounding a patch, and negatively associated with the amount of grassland surrounding a patch. Variation in small mammal community composition largely was governed by differences in habitat structure at the landscape scale, rather than differences in vegetation structure at the local scale. We suggested that managers interested in influencing small mammal abundance in grasslands employ tools such as prescribed fire to decrease litter depth if increased small mammal abundance is desired, or increase plant diversity by sowing a high diversity of seeds to depress small mammal abundance.
The properties and environment of very young galaxies in the local Universe
Authors: Trevisan M , Mamon G A , Thuan T X , Ferrari F , Pilyugin L S , Ranjan A
Published: January 2021

In the local Universe, there are a handful of dwarf compact star-forming galaxies with extremely low oxygen abundances. It has been proposed that they are young, having formed a large fraction of their stellar mass during their last few hundred Myr. However, little is known about the fraction of young stellar populations in more massive galaxies. In a previous article, we analysed  404 000 Sloan Digital Sky Survey spectra to identify a surprisingly large sample of more massive very young galaxies (VYGs), defined to have formed at least $50{{\ \rm per\ cent}}$ of their stellar mass within the last 1 Gyr. Here, we investigate in detail the properties of a subsample of 207 galaxies that are VYGs according to all three of our spectral models. We compare their properties with those of control sample galaxies (CSGs). We find that VYGs tend to have higher surface brightness and to be more compact, dusty, asymmetric, and clumpy than CSGs. Analysis of a subsample with H i detections reveals that VYGs are more gas rich than CSGs. VYGs tend to reside more in the inner parts of low-mass groups and are twice as likely as CSGs to be interacting with a neighbour galaxy. On the other hand, VYGs and CSGs have similar gas metallicities and large-scale environments (relative to filaments and voids). These results suggest that gas-rich interactions and mergers are the main mechanisms responsible for the recent triggering of star formation in low-redshift VYGs, except for the lowest mass VYGs, where the starbursts would arise from a mixture of mergers and gas infall.
NGTS and HST insights into the long-period modulation in GW Librae
Authors: Chote P , Gänsicke B T , McCormac J , Aungwerojwit A , Bayliss D , Burleigh M R , Casewell S L , Eigmüller Ph , Gill S , Goad M R , Hermes J J , Jenkins J S , Mukadam A S , Poshyachinda S , Raynard L , Reichart D E , Szkody P , Toloza O , West R G , Wheatley P J
Published: January 2021

Light curves of the accreting white dwarf pulsator GW Librae spanning a 7.5-month period in 2017 were obtained as part of the Next-Generation Transit Survey. This data set comprises 787 h of photometry from 148 clear nights, allowing the behaviour of the long (hours) and short-period (20 min) modulation signals to be tracked from night to night over a much longer observing baseline than has been previously achieved. The long-period modulations intermittently detected in previous observations of GW Lib are found to be a persistent feature, evolving between states with periods ≃ 83 min and 2–4 h on time-scales of several days. The 20 min signal is found to have a broadly stable amplitude and frequency for the duration of the campaign, but the previously noted phase instability is confirmed. Ultraviolet observations obtained with the Cosmic Origin Spectrograph on-board the Hubble Space Telescope constrain the ultraviolet-to-optical flux ratio to ≃5 for the 4 h modulation, and ≲1 for the 20 min period, with caveats introduced by non-simultaneous observations. These results add further observational evidence that these enigmatic signals must originate from the white dwarf, highlighting our continued gap in theoretical understanding of the mechanisms that drive them.
MusE GAs FLOw and Wind V. The dust/metallicity-anisotropy of the circum-galactic medium
Authors: Wendt Martin , Bouché Nicolas F , Zabl Johannes , Schroetter Ilane , Muzahid Sowgat
Published: January 2021

We investigate whether the dust content of the circum-galactic medium (CGM) depends on the location of the quasar sightline with respect to the galaxy major-axis using 13 galaxy-Mg ii absorber pairs (9–81 kpc distance) from the MusE GAs FLOw and Wind (MEGAFLOW) survey at 0.4 < z < 1.4. The dust content of the CGM is obtained from [Zn/Fe] using ultraviolet and visual echelle spectrograph data. When a direct measurement of [Zn/Fe] is unavailable, we estimate the dust depletion from a method that consists in solving for the depletion from multiple singly ionized ions (e.g. Mn ii, Cr ii, and Zn ii) since each ion depletes on dust grains at different rates. We find a positive correlation between the azimuthal angle and [Zn/Fe] with a Pearson’s r = 0.70 ± 0.14. The sightlines along the major axis show [Zn/Fe] < 0.5, whereas the [Zn/Fe] is > 0.8 along the minor axis. These results suggest that the CGM along the minor axis is on average more metal enriched (by ≈ 1 dex) than the gas located along the major axis of galaxies provided that dust depletion is a proxy for metallicity. This anisotropic distribution is consistent with recent results on outflow and accretion in hydro-dynamical simulations.
frost: a momentum-conserving CUDA implementation of a hierarchical fourth-order forward symplectic integrator
Authors: Rantala Antti , Naab Thorsten , Springel Volker
Published: January 2021

We present a novel hierarchical formulation of the fourth-order forward symplectic integrator and its numerical implementation in the GPU-accelerated direct-summation N-body code frost. The new integrator is especially suitable for simulations with a large dynamical range due to its hierarchical nature. The strictly positive integrator sub-steps in a fourth-order symplectic integrator are made possible by computing an additional gradient term in addition to the Newtonian accelerations. All force calculations and kick operations are synchronous so the integration algorithm is manifestly momentum-conserving. We also employ a time-step symmetrization procedure to approximately restore the time-reversibility with adaptive individual time-steps. We demonstrate in a series of binary, few-body and million-body simulations that frost conserves energy to a level of |ΔE/E| ∼ 10−10 while errors in linear and angular momentum are practically negligible. For typical star cluster simulations, we find that frost scales well up to $N_\mathrm{GPU}^\mathrm{max}\sim 4\times N/10^5$ GPUs, making direct-summation N-body simulations beyond N = 106 particles possible on systems with several hundred and more GPUs. Due to the nature of hierarchical integration, the inclusion of a Kepler solver or a regularized integrator with post-Newtonian corrections for close encounters and binaries in the code is straightforward.
Detection of supernova remnants in NGC 4030
Authors: Cid Fernandes R , Carvalho M S , Sánchez S F , de Amorim A , Ruschel-Dutra D
Published: January 2021

MUSE-based emission-line maps of the spiral galaxy NGC 4030 reveal the existence of unresolved sources with forbidden line emission enhanced with respect to those seen in its own H ii regions. This study reports our efforts to detect and isolate these objects and identify their nature. Candidates are first detected as unresolved sources on an image of the second principal component of the H β, [O iii] 5007, H α, [N ii] 6584, [S ii] 6716, 6731 emission-line data cube, where they stand out clearly against both the dominant H ii region population and the widespread diffuse emission. The intrinsic emission is then extracted accounting for the highly inhomogeneous emission-line ‘background’ throughout the field of view. Collisional to recombination line ratios like [S ii]/H α, [N ii]/H α, and [O i]/H α tend to increase when the background emission is corrected for. We find that many (but not all) sources detected with the principal component analysis have properties compatible with supernova remnants (SNRs). Applying a combined [S ii]/H α and [N ii]/H α classification criterion leads to a list of 59 sources with SNR-like emission lines. Many of them exhibit conspicuous spectral signatures of SNRs around 7300 Å, and a stacking analysis shows that these features are also present, except weaker, in other cases. At nearly 30 Mpc, these are the most distant SNRs detected by optical means to date. We further report the serendipitous discovery of a luminous (MV ∼ −12.5), blue, and variable source, possibly associated with a supernova impostor.