bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mutation-Selection Balance Under Genomic Imprinting at an Autosomal Locus
Authors: Spencer Hamish G 
Published: January 2021

Abstract
I model the effect of genomic imprinting on the equilibrium allele frequencies at an autosomal diallelic locus subject to viability selection and mutation. The population size is assumed to be very large; male and female mutation rates may be unequal. Different models examine cases of the inactivation of one gene (with both complete and partial penetrance) and of differential expression of genes according to the parent of origin. In the simplest cases the frequency of the deleterious allele is approximately twice that of a dominant nonimprinting mutant, but considerably less than that of a recessive nonimprinting mutant. Under imprinting, selection and unequal mutation rates interact: other things being equal, male-biased mutation leads to lower mutant frequencies under maternal imprinting and higher frequencies under paternal imprinting. I also model cases where just one allele is imprintable (and the other not). These models allow us to predict the frequency of a failure to imprint in a normally imprinting system, as well as the frequency of imprinting at a standard nonimprinting locus.
An Empirical Evaluation of Genetic Distance Statistics Using Microsatellite Data From Bear (Ursidae) Populations
Authors: Paetkau David , Waits Lisette P , Clarkson Peter L , Craighead Lance , Strobeck Curtis 
Published: January 2021

Abstract
A large microsatellite data set from three species of bear (Ursidae) was used to empirically test the performance of six genetic distance measures in resolving relationships at a variety of scales ranging from adjacent areas in a continuous distribution to species that diverged several million years ago. At the finest scale, while some distance measures performed extremely well, statistics developed specifically to accommodate the mutational processes of microsatellites performed relatively poorly, presumably because of the relatively higher variance of these statistics. At the other extreme, no statistic was able to resolve the close sister relationship of polar bears and brown bears from more distantly related pairs of species. This failure is most likely due to constraints on allele distributions at microsatellite loci. At intermediate scales, both within continuous distributions and in comparisons to insular populations of late Pleistocene origin, it was not possible to define the point where linearity was lost for each of the statistics, except that it is clearly lost after relatively short periods of independent evolution. All of the statistics were affected by the amount of genetic diversity within the populations being compared, significantly complicating the interpretation of genetic distance data.
A CASE OF HIGH RATE OF SPONTANEOUS MUTATION AFFECTING VIABILITY IN DROSOPHILA MELANOGASTER
Authors: Kidwell Margaret Gale , Kidwell J F , Nei M 
Published: January 2021

ABSTRACT
A spontaneous lethal mutation rate approximately twenty to thirty times greater than normal has been discovered in second and third chromosomes derived from an irradiated isogenic line and paired with marked inversion chromosomes. Mutations resulting in reductions of viability of varying magnitude short of complete lethality apparently also occur at a very high rate in the third but not in the second chromosome. The pattern of accumulation of lethal mutations over several generations and viability frequency distributions within generations have been studied in a number of independent experiments. High mutation rate occurs in heterozygous isogenic-derived second and third chromosomes, either together or apart, irrespective of the genetic constitution of nonhomologous chromosomes. High mutation rates were not observed using the same methods with chromosomes of an inbred line from a different source. The possible mechanisms responsible for these results are discussed.
INFLUENCE OF B LOCUS BLOOD GROUPS ON ADULT MORTALITY AND EGG PRODUCTION IN THE WHITE LEGHORN CHICKEN
Authors: Nordskog A W , Rishell W A , Briggs D M 
Published: January 2021

ABSTRACT
The influence of the B locus blood group on adult viability and egg production was studied in two White Leghorn populations (S1 and S2) synthesized from inbred line crosses. Each line segregated for four B alleles. Four homozygotes and six heterozygotes were produced in each line over a five-year period, and for an additional three years tests on certain blood-group combinations were continued. A total of 4371 birds were included in the study. Greatest differences in blood groups were found in the S1 line, with the B2 and B21 alleles seemingly having favorable effects and with B1 having unfavorable effects. The B1 homozygote was consistently the lowest in egg production (53.2%) and highest adult mortality (40.4%). The relative spread in standard deviation units between the B1 and B2 homozygotes was more than three times greater in adult mortality than in egg production; B2 was incompletely dominant to B1. Within the S1 line, the superiority of the heterozygotes was mainly a consequence of the poor fitness of the B1 homozygote, suggesting that in a random-mated population B1 would be maintained only by mutation and not by a polymorphic mechanism.—Over the eight years of the experiment, adult viability of the B1 homozygote improved 4.4% per year (P&lt;0.05). Assuming this regression results from natural selection, either of two hypotheses can account for the results: (1) The B locus is pleiotropic with natural selection for many B modifiers, and (2) the B locus is neutral but linked to a major fitness locus.
A QUANTITATIVE ANALYSIS OF THE GENETICS OF RESTING BLOOD LACTIC ACID LEVELS IN MICE
Authors: Hatchell Patricia L , MacInnes James W 
Published: January 2021

ABSTRACT
Resting blood lactate levels were measured in inbred mouse strains, their F1, and several of their segregating generations to determine whether the level of lactic acid is influenced by genetic factors. The inbred strains in each of the two sets used differed significantly from one another for this character. Only one strain showed a significant sex difference. The data could not be fully analyzed because of the failure to fulfill Mather's first criterion for an adequate scale. Nonallelic interactions, in particular, additive x dominance and dominance x dominance, were found to influence the generation means. Genotype x environment interaction was detected and eliminated by log transformation. Negative heterosis was exhibited by all but one noninbred generation.—The data suggest that genes influencing the character are dispersed between the parental lines and that interactions are predominantly of the duplicate kind. A buffering system by which lactate levels are kept at a minimum is proposed.
GENETIC ANALYSES OF HEAT-SENSITVE PAWN MUTANTS OF PARAMECIUM AURELIA
Authors: Chang Sheng-Yung , Kung Ching 
Published: January 2021

ABSTRACT
Heat-sensitive Pawn (ts Pawns) of Paramecium aurelia behaved normally when grown at 23° but failed to avoid strong stimuli at 35°. Four of the five ts Pawn lines tested were found to be allelic at a locus known also to carry temperature-independent Pawn mutations. The fifth ts Pawn line complemented all the conditional and unconditional Pawn mutants of the two known loci. This result, together with the patterns of F2 segregation from various crosses, suggested the existence of a third Pawn locus. An additive effect of the unlinked ts Pawn genes was observed. These findings and the significance of ts Pawns as experimental material in behavioral and physiological research are discussed.
HOMOEOSIS IN DROSOPHILA. I. COMPLEMENTATION STUDIES WITH REVERTANTS OF NASOBEMIA
Authors: Denell R E 
Published: January 2021

ABSTRACT
A number of homoeotic mutants have been localized to the proximal right arm of chromosome 3 of Drosophila melanogaster. These include seven alleles of Antennapedia (Antp), which is associated with a transformation of antennae into legs; Nasobemia (Ns), which causes the same phenotype as Antp but was considered by Gehring (1966) not to be an allele; and three genes causing a transformation of second and third legs into first legs: Extra sex comb (Scx), Polycomb (Pc), and Multiple sex comb (Msc.). The alleles of Antp and Scx share a common recessive lethal effect, and Pc maps 0.2-0.3 units to the left of Scx.—In the present investigation, rearrangements associated with the reversion of Ns suggest that its cytological location is in or just distal to salivary chromosome doublet 84B1-2. Although Ns is viable when homozygous, four of its revertants share a common recessive lethal effect. These revertants fail to complement the recessive lethality of AntpB and Scx. Furthermore, they show a complex pattern of functional interaction with Pc and with Humeral (Hu), a dominant mutation associated with a rearrangement with one breakpoint just distal to 84B1-2. Finally, analysis of a revertant of Msc indicates that Msc is also located very close to 84B1-2. It is concluded that Ns and Scx are alleles of Antp. Pc shows many functional similarities to the Antp locus, but is probably not allelic. Evidence is presented that these dominant homoeotic genes are neomorphic in nature.
THE INTERACTION OF TWO COMPLEX LOCI, ZESTE AND BITHORAX IN DROSOPHILA MELANOGASTER
Authors: Kaufman T C , Tasaka S E , Suzuki D T 
Published: January 2021

ABSTRACT
It has been found that certain alleles of the zeste locus (za 1-1.0) have no phenotype of their own, but interact with certain alleles at the bithorax locus (bx 3-58.8). This interaction takes the form of an enhancement of the homeotic bx phenotype to a more extreme form—i.e., the metathorax is transformed into mesothorax in varying degrees depending on the bx allele used. This enhancement is somewhat reminiscent of the transvection effect described by Lewis (1954). The characterization of the interaction thus far has shown that the enhancement only effects bx alleles which arise spontaneously, whereas the origin of the za allele is unimportant. The gene claret nondisjunctional was used for the production of gynandromorphs which showed that the enhancing ability of za, like the eye pigment change caused by z, is autonomous. The enhancement of one specific allele (bx34e), which is temperature-sensitive, has allowed a delineation of the temperature-sensitive period of the bithorax locus to a period extending from the middle of the second larval instar to the middle of the third larval instar. These results, as well as those of other enhancer and suppressor systems in Drosophila, have revealed the possibility of the involvement of heterocyclic compounds in the control of cell determination and fate in Drosophila melanogaster.
DEVELOPMENTAL AND GENETIC STUDIES ON KYNURENINE HYDROXYLASE FROM DROSOPHILA MELANOGASTER
Authors: Sullivan David T , Kitos Robert J , Sullivan Marie C 
Published: January 2021

ABSTRACT
The level of kynurenine hydroxylase was measured throughout the development of wild type and the eye color mutants v, cn, st, ltd, cd, kar, w, ca, bri and pP of Drosophila melanogaster. In all cases except cn a bimodal distribution of enzyme activity during development was observed. Activity is initially detectable in second instar. A maximum is reached in early third instar. Activity declines prior to puparium formation. Shortly after pupation, activity rises dramatically to reach a maximum about five times the peak larval level. Maximum activity persists for a short time, and then falls sharply prior to emergence. No activity is detectable in cn, cn3, or cn35K. In pupae which have zero, one, two or three doses of the cn + allele, activity is proportional to the number of the + alleles. This provides further evidence that the cn locus contains the structural gene for kynurenine hydroxylase. Kynurenine hydroxylase is a useful gene product for studying the events of imaginal disc differentiation.
UNSTABLE DIPLOIDS OF NEUROSPORA AND A MODEL FOR THEIR SOMATIC BEHAVIOR
Authors: Smith David A 
Published: January 2021

ABSTRACT
When ascospores from crosses of certain strains were germinated under conditions selective for heterozygosity of complementing markers on one linkage group, a portion of the resulting colonies were also heterozygous for unselected markers on other chromosomes, implying multiple disomy. The frequency of disomy and the pattern of marker homozygosity are consistent with most or all multiple disomics having originated as complete diploids following nondisjunction at meiosis I. The production of diploid ascospores in these strains is apparently under polygenic control. The diploids are highly unstable and do not differ from n+1 disomics in rates and mechanisms of haploidization and mitotic crossing over.
TRANSLOCATIONS, THE PREDOMINANT CAUSE OF TOTAL STERILITY IN SONS OF MICE TREATED WITH MUTAGENS
Authors: Cacheiro Nestor L A , Russell Liane Brauch , Swartout Margaret S 
Published: January 2021

ABSTRACT
Histological and cytological analyses of the testes were carried out in 42 sterile sons of males treated in the spermatozoal or spermatid stage with 250 mg/kg ethyl methanesulfonate (EMS) alone or after prefeeding with butylated hydroxytoluene (BHT); or treated with 200 R X-rays. Of the 42 sterile males, 17 had some mature spermatids, nine were blocked at diakinesis, 15 were blocked in pachytene, and one lacked spermatogenic cells altogether, having Sertoli cells only. Mitotic (spermatogonial) metaphases could therefore be analyzed in 41 of the males and meiotic configurations in 26.—(1) None of the males showed abnormalities in chromosome number, such as monosomy, trisomy, or mosaicism for either of these conditions. Certain classes of chromosome abnormalities that have been found associated with male sterility in other investigations, namely trisomies, XXY's, and X-autosome translocations, are not expected from treatment of 19A + Y cells when F1 males are studied. (2) A very high percentage of the sterile males carried translocations. Direct meiotic evidence for this was found in 22 of the animals. In addition, 11 of the 16 that were blocked (or virtually blocked) in pachytene, and thus could be analyzed in mitosis only, consistently showed one abnormally short chromosome (or, one short plus one long), which presumably had resulted from unequal exchange (or sizable deficiency). Of the meiotically detected translocation males, 1 carried a T(A;Y), 17 had single autosomal translocations, and 4 had multiple autosomal rearrangements involving three, four, four, and six breaks, respectively. In addition, three males showed failure of X-Y pairing. (3) Translocations that cause sterility, rather than partial sterility, in males appear to be those in which at least one of the breaks occurs close to one end of a chromosome. The mitotic and meiotic evidences for this were found to be correlated. (4) It is proposed that many cases of induced F1 male sterility may be the result of position effects produced when paracentromeric regions are translocated to euchromatic regions of certain other chromosomes. Since many translocations that produce partial sterility in the female cause complete sterility in the male, the male must be assumed to be more susceptible to disturbances of fertility by the postulated mechanism. (5) There is evidence that EMS, especially in the lower dose range, more often breaks chromosomes near one of their ends than does X-irradiation.
THE MECHANISM OF HETEROKARYOTIC GROWTH IN VERTICILLIUM DAHLIAE
Authors: Puhalla John E , Mayfield John E 
Published: January 2021

ABSTRACT
Heterokaryons of Verticillium dahliae, forced between complementary auxotrophs, were stable at 21° and resembled the wild type morphologically. In such heterokaryons the hyphal cells were predominantly uninucleate, and no nuclear migration from cell to cell was observed. Heterokaryosis was apparently confined to binucleate, interhyphal, anastomosed cells that arose 1-2 mm behind the colony front. Such anastomosed cells thereby fed and maintained large homokaryotic areas including the colony edge. This stable mosaic colony is in sharp contrast to the heterokaryon of Neurospora.—Heterokaryons of V. dahliae cannot continue growth at 30° because the high temperature prevents hyphal anastomosis. Heterozygous diploids sector out from heterokaryons after 8-12 days at 30°. Interhyphal anastomosed cells are apparently the site of karyogamy.
Genomic regions associated with microdeletion/microduplication syndromes exhibit extreme diversity of structural variation
Authors: Mostovoy Yulia , Yilmaz Feyza , Chow Stephen K , Chu Catherine , Lin Chin , Geiger Elizabeth A , Meeks Naomi J L , Chatfield Kathryn C , Coughlin Curtis R , Surti Urvashi , Kwok Pui-Yan , Shaikh Tamim H 
Published: January 2021

AbstractSegmental duplications (SDs) are a class of long, repetitive DNA elements whose paralogs share a high level of sequence similarity with each other. SDs mediate chromosomal rearrangements that lead to structural variation in the general population as well as genomic disorders associated with multiple congenital anomalies, including the 7q11.23 (Williams–Beuren Syndrome, WBS), 15q13.3, and 16p12.2 microdeletion syndromes. Population-level characterization of SDs has generally been lacking because most techniques used for analyzing these complex regions are both labor and cost intensive. In this study, we have used a high-throughput technique to genotype complex structural variation with a single molecule, long-range optical mapping approach. We characterized SDs and identified novel structural variants (SVs) at 7q11.23, 15q13.3, and 16p12.2 using optical mapping data from 154 phenotypically normal individuals from 26 populations comprising five super-populations. We detected several novel SVs for each locus, some of which had significantly different prevalence between populations. Additionally, we localized the microdeletion breakpoints to specific paralogous duplicons located within complex SDs in two patients with WBS, one patient with 15q13.3, and one patient with 16p12.2 microdeletion syndromes. The population-level data presented here highlights the extreme diversity of large and complex SVs within SD-containing regions. The approach we outline will greatly facilitate the investigation of the role of inter-SD structural variation as a driver of chromosomal rearrangements and genomic disorders.
Inference of population genetic parameters from an irregular time series of seasonal influenza virus sequences
Authors: Croze Myriam , Kim Yuseob 
Published: January 2021

Abstract
Basic summary statistics that quantify the population genetic structure of influenza virus are important for understanding and inferring the evolutionary and epidemiological processes. However, the sampling dates of global virus sequences in the last several decades are scattered nonuniformly throughout the calendar. Such temporal structure of samples and the small effective size of viral population hampers the use of conventional methods to calculate summary statistics. Here, we define statistics that overcome this problem by correcting for the sampling-time difference in quantifying a pairwise sequence difference. A simple linear regression method jointly estimates the mutation rate and the level of sequence polymorphism, thus providing an estimate of the effective population size. It also leads to the definition of Wright’s FST for arbitrary time-series data. Furthermore, as an alternative to Tajima’s D statistic or the site-frequency spectrum, a mismatch distribution corrected for sampling-time differences can be obtained and compared between actual and simulated data. Application of these methods to seasonal influenza A/H3N2 viruses sampled between 1980 and 2017 and sequences simulated under the model of recurrent positive selection with metapopulation dynamics allowed us to estimate the synonymous mutation rate and find parameter values for selection and demographic structure that fit the observation. We found that the mutation rates of HA and PB1 segments before 2007 were particularly high and that including recurrent positive selection in our model was essential for the genealogical structure of the HA segment. Methods developed here can be generally applied to population genetic inferences using serially sampled genetic data.
Polynomial Roth Theorems on Sets of Fractional Dimensions
Authors: Fraser Robert , Guo Shaoming , Pramanik Malabika 
Published: January 2021

Abstract
Let $E\subset{\mathbb{R}}$ be a closed set of Hausdorff dimension $\alpha \in (0, 1)$. Let $P: {\mathbb{R}}\to{\mathbb{R}}$ be a polynomial without a constant term whose degree is bigger than one. We prove that if $E$ supports a probability measure satisfying certain dimension condition and Fourier decay condition, then $E$ contains three points $x, x+t, x+P(t)$ for some $t&gt;0$. Our result extends the one of Łaba and Pramanik [ 11] to the polynomial setting, under the same assumption. It also gives an affirmative answer to a question in Henriot et al. [ 7].
Weighted Spectral Cluster Bounds and a Sharp Multiplier Theorem for Ultraspherical Grushin Operators
Authors: Casarino Valentina , Ciatti Paolo , Martini Alessio 
Published: January 2021

Abstract
We study degenerate elliptic operators of Grushin type on the $d$-dimensional sphere, which are singular on a $k$-dimensional sphere for some $k &lt; d$. For these operators we prove a spectral multiplier theorem of Mihlin–Hörmander type, which is optimal whenever $2k \leq d$, and a corresponding Bochner–Riesz summability result. The proof hinges on suitable weighted spectral cluster bounds, which in turn depend on precise estimates for ultraspherical polynomials.
The American College of Radiology/Society of Breast Imaging Updated Fellowship Training Curriculum for Breast Imaging
Authors: Katzen Janine T , Grimm Lars J , Brem Rachel F 
Published: January 2021

Abstract
Since the publication of the most recent breast imaging resident and fellowship curriculum in 2013, there have been widespread changes to the field of breast imaging. Screen-film mammography has been nearly completely replaced, and there has been widespread adoption of breast MRI and digital breast tomosynthesis. Fellowship training programs are increasingly one year in length, which accommodates the rapidly evolving subspecialized field of breast imaging. Recent surveys have identified deficits in nonclinical training related to patient communication and practice audits. This updated fellowship curriculum focuses on four discrete skill sets: clinical, noninterpretive, collaborative, and scholarly. Updates to the clinical curriculum include familiarity with new and emerging imaging technologies and biopsy techniques, as well as a more comprehensive understanding of breast pathology and appropriate follow-up and/or treatment recommendations. There is an increased focus on noninterpretive skills related to the practice audit and quality control. A formal communication curriculum tailored toward discussions with patients is highly recommended. The collaborative value of multidisciplinary care and the benefits of mentorship are emphasized. Finally, scholarly activities including both the opportunity for teaching and research, as well as dedicated lectures and journal clubs, will establish a platform for lifelong learning. This updated curriculum, which has been approved by the Executive Committee of the American College of Radiology and the Society of Breast Imaging Board of Directors, is designed to develop well-rounded fellowship graduates who are positioned to be breast imaging leaders within their future practices.