bluuebunny/crossref_metadata_2025_split huggingface dataset:
GENE-ENZYME RELATIONS OF TRYPTOPHAN MUTANTS IN STREPTOMYCES COELICOLOR A3(2)
Authors: Smithers Charles M , Engel Paulinus P 
Published: January 2021

ABSTRACT
Mutations in twenty-eight tryptophan mutants of S. coelicolor A3(2) were mapped relative to the nearest flanking markers. Mutants lacking single enzymatic activities for phosphoribosyltransferase, phosphoribosylanthranilate isomerase, indodeglycerol phosphate synthase, tryptophan synthase A and tryptophan synthase B were identified.
POSITIVE SELECTION FOR MATING WITH FUNCTIONAL HETEROKARYONS IN TETRAHYMENA PYRIFORMIS
Authors: Bruns Peter J , Brussard Trudy B 
Published: January 2021

ABSTRACT
Allelic assortment of Tetrahymena pyriformis makes possible the isolation of cells which contain both a heterozygous germ line nucleus and a somatic nucleus which expresses phenotypes of only one member of allelic pairs. Cycloheximide-sensitive segregants have been isolated from the vegetative progeny of cells heterozygous for a dominant mutation conferring resistance to cycloheximide; such segregants are called functional heterokaryons. Since progeny from crosses of these cells are cycloheximide-resistant, addition of the drug provides positive selection for successful exconjugants. The timing for expression of the new phenotype during conjugation is presented and used to identify what appear to be immature progeny of round one mating in genomic exclusion. Usefulness of functional heterokaryons in a number of genetic and developmental studies is discussed.
BISEXUAL MATING BEHAVIOR IN A DIPLOID OF SACCHAROMYCES CEREVISIAE: EVIDENCE FOR GENETICALLY CONTROLLED NON-RANDOM CHROMOSOME LOSS DURING VEGETATIVE GROWTH
Authors: Haber James E 
Published: January 2021

ABSTRACT
A diploid strain of Saccharomyces cerevisiae has been isolated which exhabits bisexual mating behavior. The strain mates with either a or α strains with a relative mating efficiency of 1 to 2%. The efficiency of mating is correlated with the frequency with which subclones of this strain revert to a single mating type. Crosses of the bisexual diploid with a/a or α/α diploids yield bisexual segregants with a frequency of approximately 3%. Analysis of the segregation of the mating type alleles and other markers on chromosome III indicates that the primary event which leads to the bisexual phenotype is the loss of one homolog of chromosome III during vegetative growth to produce a monosomic (2n-1) diploid. Evidence is presented that the loss of chromosome I11 and possibly of other chromosomes during vegetative growth is affected by a recessive nuclear gene-her (hermaphrodite)—which is not closely linked to the mating type locus.
AN EMS-SENSITIVITY FACTOR IN MAIZE CONDITIONING ALBINO LEAF STRIPES
Authors: Efron Y 
Published: January 2021

ABSTRACT
A description is given for a recessive EMS-sensitivity factor conditioning albino leaf stripes. In the homozygous condition, there is low frequency of spontaneous leaf stripes. EMS, depending on the concentration, increases markedly the frequency of the stripes in 100% of the treated plants. The effects of EMS, given to the seeds, starts to appear from the 6th to 7th leaf and persists in all the leaves throughout the life cycle of the M1 plants. Only about 20-25% of the M2 plants showed some variegation. These variegated M2 plants were not distributed at random among the different ear-to-row M2 rows.
FURTHER ANALYSIS OF COMPLEX ALLOZYME POLYMORPHISMS IN A BARLEY POPULATION
Authors: Weir B S , Allard R W , Kahler A L 
Published: January 2021

ABSTRACT
New theory has recently been developed for two-locus models. In the light of this theory, an earlier analysis of esterase allozyme data from an experimental barley population has been modified to take proper account of initial gametic phase (linkage) disequilibria. The results show that the directions in which two-locus genotypic frequencies deviated from products of one-locus frequencies in this population followed those predicted by neutral descent theory. The observed departures were, however, much larger in size than predicted by the new descent measure theory, indicating that selection is operating in the population.
ULTRAVIOLET MUTAGENESIS AND ITS REPAIR IN AN ESCHERICHIA COLI STRAIN CONTAINING A NONSENSE CODON
Authors: Person Stanley , McCloskey John Allen , Snipes Wallace , Bockrath Richard C 
Published: January 2021

ABSTRACT
Ultraviolet mutagenesis and its repair were studied mainly in WU36-10-89, a uvr - strain of Escherichia coli containing a UAG mutation in a gene for leucine biosynthesis. Following ultraviolet (UV) irradiation revertants appearing with or without direct photoreactivation (PR) were classified according to the presence and type of suppressor they contained. We find UV mutation production to be quite specific. An analysis of revertants produced by UV indicates they are formed mainly from GC → AT and that the miscoding is due to a cytosine residue at the site of mutation in a cytosine-thymine (CT) dimer. We propose that the dimer serves as template during some aspects of repair replication and at the time of replication the C in the dimer directs the insertion of A in the complementary strand. We also note that C → A and T →G changes caused by a CT dimer occur much less frequently.
MEIOSIS IN MALE DROSOPHILA MELANOGASTER I. ISOLATION AND CHARACTERIZATION OF MEIOTIC MUTANTS AFFECTING SECOND CHROMOSOME DISJUNCTION
Authors: Gethmann Richard C 
Published: January 2021

ABSTRACT
Two second chromosome, EMS-induced, meiotic mutants which cause an increase in second chromosome nondisjunction are described. The first mutant is recessive and causes an increase in second chromosome nondisjunction in both males and females. It causes no increase in nondisjunction of the sex chromosomes in either sex, nor of the third chromosome in females. No haplo-4-progeny were recovered from either sex. Thus, it appears that this mutant, which is localized to the second chromosome, affects only second chromosome disjunction and acts in both sexes.—The other mutant affects chromosome disjunction in males and has no effect in females. Nondisjunction occurs at the first meiotic division. Sex chromosome disjunction in the presence of this mutant is similar to that of sc4sc8, with an excess of X and nullo-XY sperm relative to Y and XY sperm. In some lines, there is an excess of nullo-2 sperm relative to diplo-2 sperm, which appears to be regulated, in part, by the Y chromosome. A normal Y chromosome causes an increase in nullo-2 sperm, where BsY does not. There is also a high correlation between second and sex chromosome nondisjunction. Nearly half of the second chromosome exceptions are also nondisjunctional for the sex chromosomes. Among the double exceptions, there is an excess of XY nullo-2 and nullo-XY diplo-2 gametes. Meiotic drive, chromosome loss and nonhomologous pairing are considered as possible explanations for the double exceptions.
GENIC VERSUS CHROMOSOMAL VARIATION IN NATURAL POPULATIONS OF DROSOPHILA SUBOBSCURA
Authors: Zouros E , Krimbas C B , Tsakas S , Loukas M 
Published: January 2021

ABSTRACT
Gametic frequencies in one mainland and one island population of D. subobscura were obtained by means of extracting wild chromosomes and subsequently analyzing them for inversions and allozymes. The high degree of cytological heterogeneity which characterizes these populations is not reflected in the genetic data. Two cases of non-random association were observed among eighteen pair-wise comparisons involving gene alleles and inversions to which the locus is linked. In both cases exchange of alleles at the locus is completely suppressed by the inversions. Four cases of linkage disequilibrium were detected among eighteen pairs of loci; two of them could best be explained as transient associations generated by random drift. The results suggest that disequilibria among enzyme loci are not widespread in natural populations—Populations with a lower degree of chromosomal variation are genetically as variable as populations with a higher degree of chromosomal variation. This observation does not support the hypothesis that selection in marginal homokaryotypic populations is for specialized homozygous genotypes.
SEX DETERMINATION IN BEES. II. ADDITIVITY OF MALENESS GENES IN APIS MELLIFERA
Authors: Chaud-Netto José 
Published: January 2021

ABSTRACT
Twenty-two randomly taken morphological characters were used in order to estimate the Mahalanobis generalized distance between diploid males, diploid workers, haploid males and triploid workers. It was found that adult diploid males are metamales and triploid females are slightly masculinized. These facts indicate that the maleness genes are slightly additive.
PLASMON MUTATIONS IN CYTOPLASMIC MALE-STERILE PEARL MILLET, PENNISETUM TYPHOIDES
Authors: Clement William M 
Published: January 2021

ABSTRACT
Spontaneous mutations from sterile to fertile were demonstrated in four different cytoplasmic male-sterile stocks of pearl millet. One stock, ASM-3, was of African origin, and the other three, LMS-1A, ASM-5, and ASM-7, all had the same cyptoplasm of Indian origin, but differed in nuclear make-up. These reversions were shown to be plasmon mutations, rather than genic in nature. ASM-3 mutated at the lowest rate, about 0.03/100 heads. LSM-1A, ASM-5, and ASM-7 all had the same cytoplasm but mutated at the respective rates of 0.15, 0.26, and 1.02/100 heads, indicating that plasmon mutation rate is strongly influenced by the nuclear environment.
HOW MANY GENES ARE SELECTED IN POPULATIONS OF DACUS OLEAE
Authors: Tsakas S , Krimbas C B 
Published: January 2021

ABSTRACT
Three natural populations of Dacus oleae have been sampled for six electrophoretically detected polymorphic genes. The distributions of the allele frequencies in the different populations were analyzed by the method suggested by Lewontin and Krakauer (1973) (the variation in space one) in order to test for selective neutrality. This method, however, which in our case showed that one or more genes are or have been subjected to selection, does not permit estimation of the number of selected loci. An improvement of this method is proposed that permits a minimum estimation of the selected genes. About a third of them seem to be selected in our material. In our case however, where a cytological analysis is not possible, genes are not differentiated from possible inversions including these genes.
Challenges in implementing emergency obstetric care (EmOC) policies: perspectives and behaviours of frontline health workers in Uganda
Authors: Mukuru Moses , Kiwanuka Suzanne N , Gibson Linda , Ssengooba Freddie 
Published: January 2021

Abstract
Uganda is among the sub-Saharan African Countries which continue to experience high preventable maternal mortality due to obstetric emergencies. Several Emergency Obstetric Care (EmOC) policies rolled out have never achieved their intended targets to date. To explore why upstream policy expectations were not achieved at the frontline during the MDG period, we examined the implementation of EmOC policies in Uganda by; exploring the barriers frontline implementers of EmOC policies faced, their coping behaviours and the consequences for maternal health. We conducted a retrospective exploratory qualitative study between March and June 2019 in Luwero, Iganga and Masindi districts selected based on differences in maternal mortality. Data were collected using 8 in-depth interviews with doctors and 17 midwives who provided EmOC services in Uganda’s public health facilities during the MDG period. We reviewed two national maternal health policy documents and interviewed two Ministry of Health Officials on referral by participants. Data analysis was guided by the theory of Street-Level Bureaucracy (SLB). Implementation of EmOC was affected by the incompatibility of policies with implementation systems. Street-level bureaucrats were expected to offer to their continuously increasing clients, sometimes presenting late, ideal EmOC services using an incomplete and unreliable package of inputs, supplies, inadequate workforce size and skills mix. To continue performing their duties and prevent services from total collapse, frontline implementers’ coping behaviours oftentimes involved improvization leading to delivery of incomplete and inconsistent EmOC service packages. This resulted in unresponsive EmOC services with mothers receiving inadequate interventions sometimes after major delays across different levels of care. We suggest that SLB theory can be enriched by reflecting on the consequences of the coping behaviours of street-level bureaucrats. Future reforms should align policies to implementation contexts and resources for optimal results.
Limit Shape of Perfect Matchings on Contracting Bipartite Graphs
Authors: Li Zhongyang 
Published: January 2021

AbstractWe consider random perfect matchings on a general class of contracting bipartite graphs by letting certain edge weights be 0 on the contracting square-hexagon lattice in a periodic way. We obtain a deterministic limit shape in the scaling limit. The results can also be applied to prove the existence of multiple disconnected liquid regions for all the contracting square-hexagon lattices with certain edge weights, extending the results proved in [ 13] for contracting square-hexagon lattices where the number of square rows in each period is either 0 or 1.
Institutional delivery and associated factors among women in Ghana: findings from a 2017–2018 multiple indicator cluster survey
Authors: Kumbeni Maxwell T , Apanga Paschal A 
Published: January 2021

Abstract

Background
Institutional delivery is essential in reducing maternal morbidity and mortality. We investigated the prevalence of institutional delivery and associated factors among women in Ghana.

Methods
National representative data from the 2017–2018 Ghana Multiple Indicator Cluster Survey was used for the analysis. The study included 3466 women, ages 15–49 y, who had a live birth in the last 2 y. Descriptive statistics were used to assess the prevalence of institutional delivery while multivariate logistic regression was used to assess the relationship between our variables of interest and institutional delivery.

Results
The prevalence of institutional delivery among women in Ghana was 77.89% (95% confidence interval [CI] 75.29 to 80.50). High-income households (adjusted odds ratio [aOR] 2.13 [95% CI 1.36 to 3.35]), attending antenatal care at least four times (aOR 2.37 [95% CI 1.54 to 3.65]) and knowing one's human immunodeficiency virus status (aOR 1.41 [95% CI 1.08 to 1.84]) were associated with higher odds of institutional delivery. Living in rural areas (aOR 0.43 [95% CI 0.27 to 0.67]), multiparity (aOR 0.59 [95% CI 0.41 to 0.85]) and no health insurance (aOR 0.57 [95% CI 0.44 to 0.74]) were associated with lower odds of institutional delivery.

Conclusions
The government of Ghana may need to focus on increasing health insurance utilization and antenatal care attendance in order to increase the coverage of institutional delivery.
Cognition, oxidative stress and vitamin B12 levels evaluation on patients under long-term omeprazole use
Authors: Dries Larissa Selbach , Haefliger Rochelli , Seibert Bruna Sherer , de Lima Angélica Gewehr , Cardoso Caroline de Oliveira , Perassolo Magda Susana 
Published: January 2021

Abstract

Objectives
To evaluate the differences concerning cognitive performance, oxidative stress and vitamin B12 levels in omeprazole users under treatment for longer than six months.

Methods
A case-control study was developed with 44 omeprazole users (OU; 81.8 % female, 66 ± 8.7 years old) and 35 nonusers (NOU; 88.6 % female, 62 ± 8.7 years old). The cognitive ability was assessed through tests approaching attention, memory and executive functions. The vitamin B12 was dosage using a chemiluminescent immunoassay and oxidative stress analysis, based on the evaluation of malondialdehyde, enzymatic activity of extracellular superoxide dismutase, glutathione peroxidase, catalase and the ferric reducing antioxidant power in plasma.

Key findings
A significant increase of the ferric reducing antioxidant power [omeprazole users (OU) group = 1690 µM ± 441 and nonusers (NOU) group = 1308 ± 616; P value=0.002] and a decrease on glutathione peroxidase levels [OU group = 0.534 (0.27–10.63) and NOU group = 71.86 (14.36–173.1); P value=0.006] were found on omeprazole users group, as well as differences on cognitive performance, with impairments on executive functions, automatic and attentional processing.

Conclusions
Long-term use of omeprazole is suggested to induce an oxidative stress condition, which causes neurotoxicity and cognitive decline.
Investors’ Attention to Corporate Governance
Authors: Iliev Peter , Kalodimos Jonathan , Lowry Michelle 
Published: January 2021

Abstract
Using unique data on investor views of EDGAR company filings, we document that many investors engage in governance research. However, investors’ monitoring is disproportionately focused on large firms and firms with meetings outside the busy spring proxy season. Using an instrumental variables approach that isolates the drop in governance attention during the busy proxy season, we show that governance research is related to investors’ monitoring of firms, through voice and exit. Moreover, governance research disciplines management, who, as a result, reduce investments and increase payouts. The concentration of attention results in joint monitoring of a relatively small subset of firms.
Physically asymmetric division of theC. eleganszygote ensures invariably successful embryogenesis
Authors: Jankele Radek , Jelier Rob , Gönczy Pierre 
Published: January 2021

AbstractAsymmetric divisions that yield daughter cells of different sizes are frequent during early embryogenesis, but the importance of such a physical difference for successful development remains poorly understood. Here, we investigated this question using the first division ofC. elegansembryos, which yields a large AB cell and a small P1cell. We equalized AB and P1sizes using acute genetic inactivation or optogenetic manipulation of the spindle positioning protein LIN-5. We uncovered that only some embryos tolerated equalization, and that there was a size asymmetry threshold for viability. Cell lineage analysis of equalized embryos revealed an array of defects, including faster cell cycle progression in P1descendants, as well as defects in cell positioning, division orientation and cell fate. Moreover, equalized embryos were more susceptible to external compression. Overall, we conclude that unequal first cleavage is essential for invariably successful embryonic development ofC. elegans.
Complexome profiling on thelpa2mutant reveals insights into PSII biogenesis and new PSII associated proteins
Authors: Spaniol Benjamin , Lang Julia , Venn Benedikt , Schake Lara , Sommer Frederik , Mustas Matthieu , Wollman Francis-André , Choquet Yves , Mühlhaus Timo , Schroda Michael 
Published: January 2021

AbstractWe have identified the homolog of LOW PSII ACCUMULATION 2 (LPA2) inChlamydomonas. AChlamydomonas lpa2mutant grew slower in low light and was hypersensitive to high light. PSII maximum quantum efficiency was reduced by 38%. Synthesis and stability of newly made PSII core subunits D1, D2, CP43, and CP47 were not impaired. Complexome profiling revealed that in the mutant CP43 was reduced to ∼23%, D1, D2, and CP47 to ∼30% of wild-type levels, while small PSII core subunits and components of the oxygen evolving complex were reduced at most by factor two. PSII supercomplexes, dimers, and monomers were reduced to 7%, 26%, and 60% of wild-type levels, while RC47 was increased ∼6-fold. Our data indicate that LPA2 acts at a step during PSII assembly without which PSII monomers and especially further assemblies become intrinsically unstable and prone to degradation. Levels of ATP synthase and LHCII were 29% and 27% higher in the mutant than in the wild type, whereas levels of the cytochromeb6fcomplex were unaltered. While the abundance of PSI core subunits and antennae hardly changed, LHCI antennae were more disconnected in thelpa2mutant, presumably as an adaptive response to reduce excitation of PSI. The disconnection of LHCA2,9 together with PSAH and PSAG was the prime response, but independent and additional disconnection of LHCA1,3-8 along with PSAK occurred as well. Finally, based on co-migration profiles, we identified three novel putative PSII associated proteins with potential roles in regulating PSII complex dynamics, assembly, and chlorophyll breakdown.One-sentence summaryWe provide evidence that theChlamydomonasLPA2 homolog acts at a step in PSII biogenesis without which PSII monomers and further assemblies become unstable and prone to degradation.
Poor adult nutrition impairs learning and memory in a parasitoid wasp
Authors: Farahani Hossein Kishani , Moghadassi Yasaman , Pierre Jean-Sebastien , Kraus Stéphane , Lihoreau Mathieu 
Published: January 2021

AbstractAnimals have evolved cognitive abilities whose impairment can incur dramatic fitness costs. While malnutrition is known to impact brain development and cognitive functions in vertebrates, little is known in insects, whose small brain appears particularly vulnerable to environmental stressors. Here, we investigated the influence of diet quality on learning and memory in the parasitoid waspVenturia canescens. Newly emerged adults were exposed for 24h to either honey, sucrose solution 20%, sucrose solution 10%, or no food, before being conditioned in an olfactory associative learning task in which an odor (orange) was associated to a reward (host larvae). Wasps fed honey showed 3.5 times higher learning performances and 1.5 times longer memory retention times than wasps fed sucrose solutions and starved wasps. Poor diets also reduced longevity and fecundity. Our results demonstrate the importance of early adult nutrition for optimal cognitive function in these parasitoid wasps that must quickly develop olfactory memories for choosing high quality hosts for their progeny.