bluuebunny/crossref_metadata_2025_split huggingface dataset:
INTERCONVERSION OF YEAST MATING TYPES II. RESTORATION OF MATING ABILITY TO STERILE MUTANTS IN HOMOTHALLIC AND HETEROTHALLIC STRAINS
Authors: Hicks James B , Herskowitz Ira 
Published: April 2021

ABSTRACT
The two mating types of the yeast Saccharomyces cerevisiae can be interconverted in both homothallic and heterothallic strains. Previous work indicates that all yeast cells contain the information to be both a and α and that the HO gene (in homothallic strains) promotes a change in mating type by causing a change at the mating type locus itself. In both heterothallic and homothallic strains, a defective α mating type locus can be converted to a functional a locus and subsequently to a functional α locus. In contrast, action of the HO gene does not restore mating ability to a strain defective in another gene for mating which is not at the mating type locus. These observations indicate that a yeast cell contains an additional copy (or copies) of α information, and lead to the "cassette" model for mating type interconversion. In this model, HM a and hmα loci are blocs of unexpressed α regulatory information, and HMα and hm a loci are blocs of unexpressed a regulatory information. These blocs are silent because they lack an essential site for expression, and become active upon insertion of this information (or a copy of the information) into the mating type locus by action of the HO gene.
LACK OF DOSAGE COMPENSATION FOR AN AUTOSOMAL GENE RELOCATED TO THE X CHROMOSOME IN DROSOPHILA MELANOGASTER
Authors: Roehrdanz Richard L , Kitchens James M , Lucchesi John C 
Published: April 2021

ABSTRACT
Aldehyde oxidase activity has been measured in flies with the structural gene for this enzyme translocated to the X chromosome. These measurements are presented as experimental evidence that, in Drosophila melanogaster, an autosomal gene relocated to the X chromosome is not dosage compensated.
GENE POLYMORPHISM IN NATURAL POPULATIONS OF DROSOPHILA PERSIMILIS
Authors: Prakash Satya 
Published: April 2021

ABSTRACT
Genetic variation at 43 loci has been studied in six different populations of Drosophila persimilis by electrophoresis of enzymes and proteins. In D. persimilis the mean proportion of polymorphic loci is 0.362, the mean proportion of heterozygous loci per individual is 0.100 and the average number of alleles per locus is 1.651. In all populations, the loci coding for the hydrolytic and other nonspecific enzymes are much more variable than the loci coding for the enzymes of the glycolytic pathway, Kreb's cycle, other specific enzymes and larval proteins. Most loci have similar allele frequency in all populations except the two loci, Amylase and Pt-12, which show a pattern of associations of different alleles with different third chromosome inversions.
GENETIC STUDIES OF ACRIDINE-INDUCED MUTANTS IN STREPTOCOCCUS PNEUMONIAE
Authors: Gasc A M , Sicard A M 
Published: April 2021

ABSTRACT
The mutagenic properties of acridines on pneumococcus are described. All seven acridines tested were mutagenic at the amiA locus conferring a resistance to 10-5 m aminopterin. The effects of quinacrine were more specifically investigated. It was observed that: mutants can be obtained only by treatment of exponentially growing cells; a sharp maximum mutagenic effect occurs at a concentration slightly lower than the bacteriostatic value; and the amount of quinacrine required to yield the maximum mutagenic effect decreases with the pH of the medium. Moreover, the number of mutants detected after quinacrine treatment varies from locus to locus. The majority of quinacrine-induced mutants are readily reverted by quinacrine, but not by nitrosoguanidine treatment. This suggests that in pneumococcus quinacrine induces mainly frameshift mutations. A further study of the revertants obtained by quinacrine treatment of quinacrine-induced mutants strengthens this interpretation: most of the revertants result from a mutation at the same site; some partial revertants exhibiting an intermediate resistance to aminopterin were found to contain two very closely linked mutated sites, each mutation conferring the maximum level of resistance to aminopterin. Thus, the majority of quinacrine-induced mutants at the amiA locus of pneumococcus consists of frameshift mutations. Nearly all of the isolated mutants induced by quinacrine as well as other acridines belong to the low efficiency class of transformation. It was concluded that the mismatch resulting from the pairing between the wild type and the frameshift-containing sequence is recognized by the excision-repair system involved in the discrimination function in a way similar to that in which it recognizes mismatched base pairs between a transition mutation and the wild-type sequence.
METABOLISM OF RIBOSOMAL RNA IN MUTANTS OF ESCHERICHIA COLI DOUBLY DEFECTIVE IN RIBONUCLEASE III AND THE TRANSCRIPTION TERMINATION FACTOR RHO
Authors: Apirion David , Neil Jeff , Ko Thong-Sung , Watson Ned 
Published: April 2021

ABSTRACT
To determine if proteins RNase III and rho, both of which can determine the 3' ends of RNA molecules, can complement each other, double mutants defective in these two factors were constructed. In all cases (four rho mutations tested) the double mutants were viable at lower temperatures, but were unable to grow at higher temperatures at which both of the parental strains grew. Genetic analyses suggested that the combination of the rnc rho (RNase III-Rho-) mutations was necessary and probably sufficient to confer temperature sensitivity on carrier strains. Physiological studies showed that synthesis and maturation of rRNA, which is greatly affected by RNase III, as well as other RNAs, was indistinguishable in rnc rho strains as compared to rnc rho + strains, thus suggesting that RNase III and rho do not complement one another in determining the 3' ends of RNA molecules. In rnc rho strains, however, the newly synthesized rRNA failed to accumulate. Thus, decay of rRNA could be the reason for the temperature sensitivity of the double mutant strains. These experiments suggest that RNase III and rho can both protect rRNA from degradation by cellular ribonucleases. They also point to the possibility that the nucleotide sequences involved in the determination of the 3' ends of RNA molecules by these two factors are not identical.
GENETIC AND PHYSIOLOGICAL ADAPTATION OF THE COPEPOD EURYTEMORA AFFINIS TO SEASONAL TEMPERATURES
Authors: Bradley Brian P 
Published: April 2021

ABSTRACT
Evidence of significant additive genetic (genic) variance in temperature tolerance of the copepod Eurytemora affinis was derived from several sources. Differences were observed between average tolerances of progeny of animals exposed and not exposed to heat shock in a power plant. Genic variance was estimated using offspring-parent regressions, full-sib, and half-sib covariances, with quite consistent results. Expressed genic variance between male progeny was always higher than that among female progeny.—The pairs of estimates obtained were as follows: female heritabilities first, 0.40 ± 0.09 and 0.84 ± 0.35 (half-sibs); 0.20 ± 0.09 and 0.79 ± 0.24 (full-sibs); 0.11 ± 0.10 and 0.89 ± 0.45 (full-sibs); 0.28 ± 0.18 and 0.78 ± 0.29 (full-sibs); 0.11 ± 0.44 and 0.72 ± 0.26 (offspring-parent regression). There was no evidence of either nonadditive genetic variance or common environmental (maternal and brood) effects, implying that the genetic variance was mostly additive and was not maintained because of heterozygous advantage.—The presence of so much genetic variance is surprising in view of the high physiological adaptation found earlier, especially in females.
MEIOTIC RECOMBINATION AND DNA SYNTHESIS IN A NEW CELL CYCLE MUTANT OF SACCHAROMYCES CEREVISIAE
Authors: Kassir Yona , Simchen Giora 
Published: April 2021

ABSTRACT
Vegetative cells carrying the new temperature-sensitive mutation cdc40 arrest at the restrictive temperature with a medial nuclear division phenotype. DNA replication is observed under these conditions, but most cells remain sensitive to hydroxyurea and do not complete the ongoing cell cycle if the drug is present during release from the temperature block. It is suggested that the cdc40 lesion affects an essential function in DNA synthesis. Normal meiosis is observed at the permissive temperature in cdc40 homozygotes. At the restrictive temperature, a full round of premeiotic DNA replication is observed, but neither commitment to recombination nor later meiotic events occur. Meiotic cells that are already committed to the recombination process at the permissive temperature do not complete it if transferred to the restrictive temperature before recombination is realized. These temperature shift-up experiments demonstrate that the CDC40 function is required for the completion of recombination events, as well as for the earlier stage of recombination commitment. Temperature shift-down experiments with cdc40 homozygotes suggest that meiotic segregation depends on the final events of recombination rather than on commitment to recombination.
POSITION EFFECTS AND VARIEGATION ENHANCERS IN AN AUTOSOMAL REGION OF DROSOPHILA MELANOGASTER
Authors: Henikoff Steven 
Published: April 2021

ABSTRACT
A dominant eye color mutation was found associated with a third chromosome inversion broken distally at or near the karmoisin (kar) locus in 87C and proximally within centric heterochromatin. Suppressibility of the mutant phenotype by an extra Y chromosome indicated that this was an example of dominant position-effect variegation. When heterozygous with deficiencies uncovering the kar locus, this inversion chromosome was found to be lethal unless a region in 87EF was also deleted. Extra Y chromosomes rescued inversion/deletion heterozygotes, while removal of the Y chromosome from heterozygous males deficient for the region in 87EF was lethal. Thus, a variegating lethal lies near the breakpoint in 87C, and a wild-type gene that enhances its variegation lies in 87EF. Furthermore, deletion of the region in 87EF was found to strongly suppress white-mottled-4 (wm4) variegation, while deletion of another region in 87BC suppressed less strongly. These results indicate that essential genes on autosomes are sensitive to position effects, and loci that enhance variegation, as defined by deficiency mapping, are very common.
PATTERNS OF GENETIC AND PHENOTYPIC SUPPRESSION OF lys2 MUTATIONS IN THE YEAST SACCHAROMYCES CEREVISIAE
Authors: Chattoo Bharat B , Palmer Edward , Ono Bun-Ichiro , Sherman Fred 
Published: April 2021

ABSTRACT
A total of 358 lys2 mutants of Saccharomyces cerevisiae have been characterized for suppressibility by the following suppressors: UAA and UAG suppressors that insert tyrosine, serine or leucine; a putative UGA suppressor; an omnipotent suppressor SUP46; and a frameshift suppressor SUF1-1. In addition, the lys2 mutants were examined for phenotypic suppression by the aminoglycoside antibiotic paromomycin, for osmotic remediability and for temperature sensitivity. The mutants exhibited over 50 different patterns of suppression and most of the nonsense mutants appeared similar to nonsense mutants previously described. A total of 24% were suppressible by one or more of the UAA suppressors, 4% were suppressible by one or more of the UAG suppressors, while only one was suppressible by the UGA suppressor and only one was weakly suppressible by the frameshift suppressor. One mutant responded to both UAA and UAG suppressors, indicating that UAA or UAG mutations at certain rare sites can be exceptions to the specific action of UAA and UAG suppressors. Some of the mutants appeared to require certain types of amino acid replacements at the mutant sites in order to produce a functional gene product, while others appeared to require suppressors that were expressed at high levels. Many of the mutants suppressible by SUP46 and paromomycin were not suppressible by any of the UAA, UAG or UGA suppressors, indicating that omnipotent suppression and phenotypic suppression need not be restricted to nonsense mutations. All of the mutants suppressible by SUP46 were also suppressible by paromomycin, suggesting a common mode of action of omnipotent suppression and phenotypic misreading.
THE FATE OF MITOCHONDRIAL LOCI IN RHO MINUS MUTANTS INDUCED BY ULTRAVIOLET IRRADIATION OF SACCHAROMYCES CEREVISIAE: EFFECTS OF DIFFERENT POST-IRRADIATION TREATMENTS
Authors: Heude M , Moustacchi E 
Published: April 2021

ABSTRACT
Three main features regarding the loss of mitochondrial genetic markers among rhomutants induced by ultraviolet irradiation are reported: (a) the frequency of loss of six loci examined increases with UV dose; (b) preferential loss of one region of the mitochondrial genome observed in spontaneous rho-mutants is enhanced by UV; and (c) the loss of each marker results from large deletions. Marker loss in rho-mutants was also investigated under conditions that modulate rho-induction. Liquid holding of irradiated exponential or stationary phase cells, as well as a split-dose regime applied to stationary phase cells, results in rho-mutants in which the loss of markers is correlated with rho-induction: the more sensitive the cells are to rho-induction, the more frequent are the marker losses among rho-clones derived from these cells. This correlation is not found in exponential-phase cells submitted to a split-dose treatment, suggesting that a different mechanism is involved in the latter case. It is known that UV-induced pyrimidine dimers are not excised in a controlled manner in mitochondrial DNA. How-ever, our studies indicate that an accurate repair mechanism (of the recombinational type ?) can lead to the restoration of mitochondrial genetic information in growing cells.
MATING-TYPE REGULATION OF METHYL METHANESULFONATE SENSITIVITY IN SACCHAROMYCES CEREVISIAE
Authors: Livi George P , Mackay Vivian L 
Published: April 2021

ABSTRACT
Heterozygosity at the mating-type locus (MAT) in Saccharomyces cerevisiae has been shown previously to enhance X-ray survival in diploid cells. We now show that a/α diploids are also more resistant to the radiomimetic agent methyl methanesulfonate (MMS) that are diploids that are homozygous at MAT (i.e., either a/a or α/α). Log-phase a/α cultures exhibit biphasic MMS survival curves, in which the more resistant fraction consists of budded cells (those cells in the S and G2 phases of the cell cycle). Survival curves for log-phase cultures of a/a or α/α diploids have little if any biphasic nature, suggesting that the enhanced S- and G2-phase repair capacity of a/α cells may be associated with heterozygosity at MAT. The survival of cells arrested at the beginning of the S phase with hydroxyurea indicates that MAT-dependent MMS repair is limited to S and G2, whereas MAT-independent repair can occur in Gl.
CLASSIFICATION OF NORMAL AND MALE-STERILE CYTOPLASMS IN MAIZE. II. ELECTROPHORETIC ANALYSIS OF DNA SPECIES IN MITOCHONDRIA
Authors: Kemble R J , Gunn R E , Flavell R B 
Published: April 2021

ABSTRACT
Mitochondrial DNA preparations were made from 31 maize lines carrying different sources of cytoplasm in the same nuclear genetic background. The DNAs were analyzed by agarose gel electrophoresis. A number of discrete low molecular weight bands were present in all lines. However, only four different DNA banding patterns were observed. These were correlated with the N, T, S and C cytoplasms defined by nuclear fertility restorer genes. Of the 31 cytoplasmic sources examined, six possessed DNA species characteristic of N cytoplasms, four possessed DNA species characteristic of T cytoplasm, 19 possessed DNA species characteristic of S cytoplasm and two possessed DNA species characteristic of C cytoplasm. This classification is in complete agreement with that based on mitochondrial translation products reported in the accompanying paper. No within-group heterogeneity was observed in the DNA banding patterns, indicating a lack of cytoplasmic variation within the four cytoplasmic groups. Attributes of the various methods available for classifying maize cytoplasms are compared and discussed.
Family Caregiving During the COVID-19 Pandemic
Authors: Beach Scott R , Schulz Richard , Donovan Heidi , Rosland Ann-Marie 
Published: April 2021

Abstract

Background and Objectives
The coronavirus disease 2019 (COVID-19) pandemic has negatively affected persons with existing chronic health conditions. The pandemic also has the potential to exacerbate the stresses of family caregiving. We compare family caregivers with noncaregivers on physical, psychosocial, and financial well-being outcomes during the pandemic and determine family caregivers most at risk for adverse outcomes.

Research Design and Methods
We conducted a cross-sectional online survey of 576 family caregivers and 2,933 noncaregivers from April to May 2020 in Pittsburgh, PA region with a national supplement. Outcome measures included concurrent anxiety, depression, fatigue, sleep disturbance, social participation, and financial well-being and perceived changes due to COVID-19 (loneliness, financial well-being, food security). We also measured sociodemographic, caregiving contextual variables, and COVID-19-related caregiver stressors (COVID Caregiver Risk Index).

Results
Controlling for sociodemographics, family caregivers reported higher anxiety, depression, fatigue, sleep disturbance, lower social participation, lower financial well-being, increased food insecurity (all p &lt; .01), and increased financial worries (p = .01). Caregivers who reported more COVID-19-related caregiver stressors and disruptions reported more adverse outcomes (all p &lt; .01). In addition, caregivers who were female, younger, lower income, providing both personal/medical care, and providing care for cognitive/behavioral/emotional problems reported more adverse outcomes.

Discussion and Implications
Challenges of caregiving are exacerbated by the COVID-19 pandemic. Family caregivers reported increased duties, burdens, and resulting adverse health, psychosocial, and financial outcomes. Results were generally consistent with caregiver stress–health process models. Family caregivers should receive increased support during this serious public health crisis.
Drivers and implications of change in an inshore multi-species fishery
Authors: Henly Lauren , Stewart James E , Simpson Stephen D 
Published: April 2021

AbstractInshore fisheries are an important source of employment and income across Europe. However, their sustainability and management efficacy are relatively understudied, particularly in a multispecies context. Management of these data-limited fisheries can be informed by assessments of standardized catch and landings per unit effort (CPUE and LPUE) data from fishery-dependent surveys. We demonstrate the utility of this approach in the first robust assessment of the sustainability and management of a multispecies inshore fishery for live wrasse (Labridae) in southern England. Our findings have wider ramifications for assessment and management of inshore fisheries, including international live wrasse fisheries, many of which are intensely exploited but have less stringent management than the fishery studied here. Using generalized linear models, we identified ecologically relevant drivers of variation in CPUE and LPUE, alongside interspecific variation in responses to fishing pressure during 2017–2019. We also highlight robust evidence of declines in the primary target species, a protogynous hermaphrodite, that are suggestive of fishery impacts driven by management-enabled selective removal of mature females. We demonstrate the need to consider ecologically similar species separately for management purposes, and account for ecogeographical variables in assessments; a failure to do so risks erroneous conclusions regarding inshore fisheries’ sustainability.
Combined Complex Skin Repair in Patient With Extensive Burns: A Case Report
Authors: Gao Xingxin , Zhang Min , Lin Yuan , Li Dehui , Zhang Liming 
Published: April 2021

Abstract
Auto-skin grafting is the current treatment of choice for extensive burns. Nevertheless, the lack of donor sites for skin grafting remains one of the greatest limiting factors for the treatment of extensively burned patients. We present the case of a 53-year-old male patient with deep and full thickness burns on 91% of the total body surface area. We used the Meek technique for split-thickness skin graft expansion to treat this patient. In order to obtain sufficient skin for grafting, we repeatedly harvested the same anatomical areas. Acceleration of burn wounds, recipient, and donor site healing was achieved by systemic treatment with recombinant human growth hormone and topical recombinant human epidermal growth factors. This combined, complex treatment modality contributed to the successful skin repair in this patient.
Inhibition of tryptophan 2,3-dioxygenase impairs DNA damage tolerance and repair in glioma cells
Authors: Reed Megan R , Maddukuri Leena , Ketkar Amit , Byrum Stephanie D , Zafar Maroof K , Bostian April C L , Tackett Alan J , Eoff Robert L 
Published: April 2021

AbstractExpression of tryptophan 2,3-dioxygenase (TDO) is a determinant of malignancy in gliomas through kynurenine (KYN) signaling. We report that inhibition of TDO activity attenuated recovery from replication stress and increased the genotoxic effects of bis-chloroethylnitrosourea (BCNU). Activation of the Chk1 arm of the replication stress response (RSR) was reduced when TDO activity was blocked prior to BCNU treatment, whereas phosphorylation of serine 33 (pS33) on replication protein A (RPA) was enhanced—indicative of increased fork collapse. Analysis of quantitative proteomic results revealed that TDO inhibition reduced nuclear 53BP1 and sirtuin levels. We confirmed that cells lacking TDO activity exhibited elevated gamma-H2AX signal and defective recruitment of 53BP1 to chromatin following BCNU treatment, which corresponded with delayed repair of DNA breaks. Addition of exogenous KYN increased the rate of break repair. TDO inhibition diminished SIRT7 deacetylase recruitment to chromatin, which increased histone H3K18 acetylation—a key mark involved in preventing 53BP1 recruitment to sites of DNA damage. TDO inhibition also sensitized cells to ionizing radiation (IR)-induced damage, but this effect did not involve altered 53BP1 recruitment. These experiments support a model where TDO-mediated KYN signaling helps fuel a robust response to replication stress and DNA damage.