bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-term results of hybrid aortic arch repair using landing zone 0: a single-centre study
Authors: Kudo Tomoaki , Kuratani Toru , Shimamura Kazuo , Sakaniwa Ryoto , Sawa Yoshiki
Published: January 2021

OBJECTIVES

Thoracic endovascular aortic repair (TEVAR) has been gradually extended to the aortic arch region, with improved results. However, the rates of strokes and endoleaks in a hybrid TEVAR remain high. The goal of this study was to clarify the effectiveness of a hybrid TEVAR with a zone 0 landing using our treatment strategy.

METHODS

From April 2008 to March 2020, a total of 102 patients were enrolled in this study, with a median follow-up period of 3.2 years. The procedures included total debranching TEVAR with graft replacement of the ascending aorta in 62 patients, total debranching TEVAR with ascending aorta banding in 19 patients and total debranching TEVAR without ascending aorta banding in 21 patients.

RESULTS

Thirty-day mortality and hospital deaths were 1.0% (n = 1) and 3.9% (n = 4), respectively. The rates of aortic complications and endoleaks during the first 30 days postoperatively were 8.8% (n = 9) and 4.9% (n = 5), respectively. There was no type 1a endoleak, whereas retrograde type A dissection occurred in 2 (2.0%) patients. The rate of late aortic events was 3.9% (n = 4); there were no late endoleaks or aneurysm ruptures. The 10-year survival rate was 73.7% [95% confidence interval (CI) 60.3–83.8%]. The 10-year rates of aorta-related deaths and aortic events when performing a competitive-risk analysis were 29.4% (95% CI 16.3–42.5%) and 7.2 (95% CI 23.0–51.4%), respectively.

CONCLUSIONS

Satisfactory early and long-term results of a hybrid TEVAR with a zone 0 landing were achieved using our treatment strategy. When performing hybrid TEVAR in zone 0, postoperative aortic events may be reduced by accurate preoperative assessment of the ascending aorta.
Prediction of thromboembolic events and mortality by the CHADS2 and the CHA2DS2-VASc in COVID-19
Authors: Caro-Codón Juan , Lip Gregory Y H , Rey Juan R , Iniesta Angel M , Rosillo Sandra O , Castrejon-Castrejon Sergio , Rodriguez-Sotelo Laura , Garcia-Veas Jose M , Marco Irene , Martinez Luis A , Martin-Polo Lorena , Merino Carlos , Martinez-Cossiani Marcel , Buño Antonio , Gonzalez-Valle Luis , Herrero Alicia , Lopez-de-Sa Esteban , Merino Jose L
Published: January 2021

Aims

Age, sex, and cardiovascular disease have been linked to thromboembolic complications and poorer outcomes in COVID-19. We hypothesize that CHADS2 and CHA2DS2-VASc scores may predict thromboembolic events and mortality in COVID-19.

Methods and results

COVID-19 hospitalized patients with confirmed SARS-CoV-2 infection from 1 March to 20 April 2020 who completed at least 1-month follow-up or died were studied. CHADS2 and CHA2DS2-VASc scores were calculated. Given the worse prognosis of male patients in COVID-19, a modified CHA2DS2-VASc score (CHA2DS2-VASc-M) in which 1 point was given to male instead of female was also calculated. The associations of these scores with laboratory results, thromboembolic events, and death were analysed. A total of 3042 patients (mean age 62.3 ± 20.3 years, 54.9% male) were studied and 115 (3.8%) and 626 (20.6%) presented a definite thromboembolic event or died, respectively, during the study period [median follow 59 (50–66) days]. Higher score values were associated with more marked abnormalities of inflammatory and cardiac biomarkers. Mortality was significantly higher with increasing scores for CHADS2, CHA2DS2-VASc, and CHA2DS2-VASc-M (P < 0.001 for trend). The CHA2DS2-VASc-M showed the best predictive value for mortality [area under the receiver operating characteristic curve (AUC) 0.820, P < 0.001 for comparisons]. All scores had poor predictive value for thromboembolic events (AUC 0.497, 0.490, and 0.541, respectively).

Conclusion

The CHADS2, CHA2DS2-VASc, and CHA2DS2-VASc-M scores are significantly associated with all-cause mortality but not with thromboembolism in COVID-19 patients. They are simple scoring systems in everyday use that may facilitate initial ‘quick’ prognostic stratification in COVID-19.
Witnessed and unwitnessed sudden cardiac death: a nationwide study of persons aged 1–35 years
Authors: Svane Jesper , Lynge Thomas Hadberg , Hansen Carl Johann , Risgaard Bjarke , Winkel Bo Gregers , Tfelt-Hansen Jacob
Published: January 2021

Aims

The aim of this study is to compare clinical characteristics and causes of death among witnessed and unwitnessed sudden cardiac death (SCD) cases aged 1–35 years.

Methods and results

In this retrospective nationwide study, all deaths in persons aged 1–35 years in Denmark during 2000–09 were included (23.7 million person-years). Using the in-depth descriptive Danish death certificates and Danish nationwide registries, 860 cases of sudden, unexpected death were identified. Through review of autopsy reports and register data, we identified 635 cases of SCD of which 266 (42%) were witnessed and 326 (51%) were unwitnessed. In 43 cases (7%), witnessed status was missing. Clinical characteristics were overall similar between the two groups. We found a male predominance among unwitnessed SCD compared to witnessed SCD (71% and 62%, respectively, P-value 0.012), as well as more psychiatric comorbidity (20% and 13%, respectively, P-value 0.029). Unwitnessed SCD more often occurred during sleep whereas witnessed SCD more often occurred while the individual was awake and relaxed (P-value < 0.001). The autopsy rate among all SCD cases was 70% with no significant difference in autopsy rate between the two groups. Sudden unexplained death, which was the leading autopsy conclusion in both groups, was more frequent among unwitnessed SCD (P-value 0.001).

Conclusion

Several clinical characteristics and autopsy findings were similar between witnessed and unwitnessed SCD cases. Our data support the inclusion of both witnessed and unwitnessed cases in epidemiological studies of SCD cases aged 1–35 years, although the risk of misclassification is higher among unwitnessed and non-autopsied cases of SCD.
Heat shock proteins and small nucleolar RNAs are dysregulated in a Drosophila model for feline hypertrophic cardiomyopathy
Authors: Tallo Christian A , Duncan Laura H , Yamamoto Akihiko H , Slaydon Joshua D , Arya Gunjan H , Turlapati Lavanya , Mackay Trudy F C , Carbone Mary A
Published: January 2021

In cats, mutations in myosin binding protein C (encoded by the MYBPC3 gene) have been associated with hypertrophic cardiomyopathy (HCM). However, the molecular mechanisms linking these mutations to HCM remain unknown. Here, we establish Drosophila melanogaster as a model to understand this connection by generating flies harboring MYBPC3 missense mutations (A31P and R820W) associated with feline HCM. The A31P and R820W flies displayed cardiovascular defects in their heart rates and exercise endurance. We used RNA-seq to determine which processes are misregulated in the presence of mutant MYBPC3 alleles. Transcriptome analysis revealed significant downregulation of genes encoding small nucleolar RNA (snoRNAs) in exercised female flies harboring the mutant alleles compared to flies that harbor the wild-type allele. Other processes that were affected included the unfolded protein response and immune/defense responses. These data show that mutant MYBPC3 proteins have widespread effects on the transcriptome of co-regulated genes. Transcriptionally differentially expressed genes are also candidate genes for future evaluation as genetic modifiers of HCM as well as candidate genes for genotype by exercise environment interaction effects on the manifestation of HCM; in cats as well as humans.
Draft genome of the herbaceous bamboo Raddia distichophylla
Authors: Li Wei , Shi Cong , Li Kui , Zhang Qun-Jie , Tong Yan , Zhang Yun , Wang Jun , Clark Lynn , Gao Li-Zhi
Published: January 2021

Bamboos are important nontimber forest plants widely distributed in the tropical and subtropical regions of Asia, Africa, America, and Pacific islands. They comprise the Bambusoideae in the grass family (Poaceae), including approximately 1700 described species in 127 genera. In spite of the widespread uses of bamboo for food, construction, and bioenergy, the gene repertoire of bamboo still remains largely unexplored. Raddia distichophylla (Schrad. ex Nees) Chase, belonging to the tribe Olyreae (Bambusoideae, Poaceae), is a diploid herbaceous bamboo with only slightly lignified stems. In this study, we report a draft genome assembly of the ∼589 Mb whole-genome sequence of R. distichophylla with a contig N50 length of 86.36 Kb. Repeat sequences account for ∼49.08% of the genome assembly, of which LTR retrotransposons occupy ∼35.99% of the whole genome. A total of 30,763 protein-coding genes were annotated in the R. distichophylla genome with an average transcript size of 2887 bp. Access to this herbaceous bamboo genome sequence will provide novel insights into biochemistry, molecular marker-assisted breeding programs, and germplasm conservation for bamboo species worldwide.
REPRESSOR AND ANTIREPRESSOR IN THE REGULATION OF STAPHYLOCOCCAL PENICILLINASE SYNTHESIS
Authors: Imsande John
Published: January 2021

5-methyltryptophan (5MT) induces penicillinase synthesis in Staphylococcus aureus. The analog is incorporated into protein by both wild-type and tryptophan-starved cells. Since normal penicillinase repressor appears to contain tryptophan even though penicillinase itself does not, it is concluded that 5MT induces penicillinase synthesis by becoming incorporated into the penicillinase repressor and thereby inactivating the repressor. Thus biochemical data support the existence of a penicillinase repressor and indicate that penicillinase synthesis is regulated by negative control and not by positive control.—In the absence of exogenous tryptophan, staphylococcal penicillinase induction can be inhibited by 7-azatryptophan (7azaT). Because 7azaT is incorporated into protein by tryptophan-starved cells, it is concluded that 7azaT blocks penicillinase induction by inactivating a penicillinase regulatory protein into which the analog has been incorporated. Incorporation of 7azaT does not appear to inactivate the operator binding site or the effector binding site on the penicillinase repressor. Therefore, it appears that 7azaT blocks penicillinase induction by inactivating the penicillinase antirepressor, a protein required for inactivation of the penicillinase repressor and, hence, required for penicillinase induction.
THE APPARENT CONSERVATION OF THE INTERNAL LOW EFFICIENCY PROMOTER OF THE TRYPTOPHAN OPERONS OF SEVERAL SPECIES OF ENTEROBACTERIACEAE
Authors: Largen Michael , Belser William
Published: January 2021

The specific activities of the tryptophan biosynthetic enzymes were determined for eleven different species of Enterobacteriaceae grown under repressing and non-repressing conditions. In all the bacteria examined the multipliciy of derepression for the first two enzymes of the pathway was at least twofold greater than the multiplicity of derepression for the last three enzymes.
INTEGRATION EFFICIENCY IN DNA-INDUCED TRANSFORMATION OF PNEUMOCOCCUS. I. A METHOD OF TRANSFORMATION IN SOLID MEDIUM AND ITS USE FOR ISOLATION OF TRANSFORMATION-DEFICIENT AND RECOMBINATION-MODIFIED MUTANTS
Authors: Tiraby Gerard , Claverys Jean-Pierre , Sicard Michel Armand
Published: January 2021

A method of transformation on solid medium especially adapted for pneumococcus has been developed. Under specific conditions, all colonies that are allowed to grow in the presence of transforming DNA for six hours give rise to transformed bacteria. Combined with replica plating this technique has been used to isolate mutants modified with regard to recombination. Most of the mutants found are transformation-defective and show a large diversity in their response to ultraviolet light. Some of these mutants have lost their ability to take up transforming DNA. One shows a reduced yield of transformants for a given quantity of DNA taken up. Mutants that manifest altered behavior with regard to marker efficiencies have also been isolated. One of these exhibits a decrease in the transformation efficiency of only the high efficiency markers and two mutants show a decrease in the transformation efficiency of the low efficiency markers.
THE GENETIC CONTROL AND BIOCHEMICAL MODIFICATION OF CATECHOL OXIDASE IN MAIZE
Authors: Pryor Tony , Schwartz Drew
Published: January 2021

Three isozyme variants of catechol oxidase have been shown to be determined by alleles of a gene, Cx, which has been located on chromosome 10 less than 0.1 recombination units from the endosperm marker du  1.—The extractable form of the enzyme is modified by an endogeneous "modifier" which appears to function as an enzyme substrate. Enzyme and modifier are functionally isolated in intact cells. Modified enzyme has altered kinetics, does not migrate in electrophoresis and most probably results from a "tanning" of the enzyme by reaction products. The content of modifier varies in different lines and is genetically determined by gene(s) independent of Cx. Treatment with maleic hydrazide causes a ten-fold reduction in the modifier content of seedlings, allowing the enzyme to be extracted in an unmodified form which will migrate in electrophoresis.—This system of enzyme and modifier fits the requirements of hypersensitive disease resistance in plants and may provide a test system to investigate the biochemical basis of disease resistance.
THE INHERITANCE OF GOSSYPOL LEVEL IN GOSSYPIUM II: INHERITANCE OF SEED GOSSYPOL IN TWO STRAINS OF CULTIVATED GOSSYPIUM BARBADENSE L
Authors: Lee Joshua
Published: January 2021

Two strains of cultivated Gossypium barbadense L., Sea Island AS-2 and Pima S-4, were used to study the effects of alleles at two loci on the production and/or storage of gossypol in mature embryos. The normal alleles, Gl  2 and Gl  3, are "native" to G. barbadense, whereas the mutant alleles, gl  2 and gl  3, were introduced from Gossypium hirsutum L. through backcrossing. Each strain was grown in three replications per trial, and one, Sea Island AS-2, was grown in three environments. Each experiment consisted of all possible crosses, including reciprocals, of the four true-breeding genotypes, plus parents. Additive effects accounted for more than 90% of the total genetic variance for seed gossypol level in all trials. Epistatic effects, though small, were frequently significant. In G. barbadense Gl  2 and Gl  3 were associated with the production of similar amounts of gossypol, whereas previous trials with cultivated varieties of G. hirsutum showed that Gl  2 was more than twice as expressive as Gl  3. The greater average productivity of seed gossypol in cultivated G. barbadense, as compared with G. hirsutum, was attributed to greater activity at the Gl  3 locus in the former species.
ASSOCIATIONS OF ALLELES OF THE ESTERASE-1 LOCUS WITH GENE ARRANGEMENTS OF THE LEFT ARM OF THE SECOND CHROMOSOME IN DROSOPHILA ROBUSTA
Authors: Prakash Satya , Levitan Max
Published: January 2021

Evidence of strong associations of Est-1 alleles with the 2L, 2L1 and 2L3 gene arrangements of the left arm of the second chromosome in D. robusta is presented. Each gene arrangement is polymorphic for three to four Est-1 alleles. The allele frequencies differ in the 2L3 and 2L arrangements; the allele Est-1.92 is 8% in the 2L3 arrangement (n=203)—this allele is 82% in the 2L arrangement (n=203); the allele Est-11.0 is 66% and 14.8% in the 2L3 and 2L arrangements, respectively. There are no differences in allele frequencies in 2L3 arrangements from any of the widely separated seven different populations; similarly the allele frequencies in the 2L arrangement are alike in all five widely separated populations studied. The allele frequencies in the 2L1 arrangement are intermediate to those observed in the 2L3 and the 2L arrangements and show north-south clinal change. These associations between Est-1 alleles and gene arrangements of the left arm of the second chromosome are due to natural selection favoring different allele frequencies in different gene arrangements, as a result of epistatic interactions between the Est-1 locus and the loci on the gene arrangements. As expected, we observe that the proportion of heterozygotes is greater in the inversion heterokaryotypes than in the homokaryotypes.
TEMPERATURE-SENSITIVE NONSENSE SUPPRESSORS IN YEAST
Authors: Rasse-Messenguy Francine , Fink Gerald R
Published: January 2021

A single mutation leads to temperature-sensitive amber and ochre suppression in yeast. This mutation maps in or near the SUP4 gene on chromosome X.
FORMATION OF MEGACHROMOSOMES FROM HETEROCHROMATIC BLOCKS OF NICOTIANA TOMENTOSIFORMIS
Authors: Burns J A , Gerstel D U
Published: January 2021

A heterochromatic block (HB) from N. otophora occasionally undergoes great enlargement to form a "megachromosome" in hybrids and hybrid derivatives with N. tabacum. This paper shows that the two large HB's of closely related N. tomentosiformis, and perhaps a smaller one, also have the same capability. The evidence that both large HB's form megachromosomes is twofold. In a segregating backcross population from a parent possessing the two large HB's, all segregants with one block produced megachromosomes at metaphase or large heterochromatic clumps at interphase. Second, those segregants which possessed both heterochromatic blocks produced megachromosomes of two visibly different types. Proliferation to make megachromosomes thus may not be the property of merely one particular segment but a more common property of heterochromatin in a hybrid or otherwise disturbed background.
GENES FOR DWARFNESS IN WHEAT, TRITICUM AESTIVUM L
Authors: Fick G N , Qualset C O
Published: January 2021

The genetic control of plant height was studied in crosses of four spring wheats involving the standard height variety Ramona 50 and short-statured selections Olesen, D6301, and D6899. Data from parent, F1, F2, and F3 populations indicated that four independently segregating loci account for most of the differences among the four varieties. Two major genes of a highly recessive nature condition reduced height in Olesen and the Norin 10 derivative D6301. Olesen also carries a third dwarfing gene which is partially dominant in its effects over genes for tallness. This gene, or a gene that acts in a similar manner, is also present in the standard height variety Ramona 50. Dwarfing in D6899, a derivative of Tom Thumb, is controlled primarily by a single gene with mainly additive effects which is not present in any of the other three varieties.

Genetic components estimated from generation means (parental, F1, F2, F3, and backcross) indicated that additive gene effects were the major component of variation in four of the six crosses, and of similar magnitude to dominance effects in another cross. The primary source of genetic variation in the cross Olesen × D6899 was due to epistasis with both additive × additive and dominance × dominance effects of major importance. The results of the generation mean analyses were consistent with the models for major-gene control of plant height based on segregation patterns.
SELECTION FOR MATING RELUCTANCE IN FEMALES OF A DIPLOID PARTHENOGENETIC STRAIN OF DROSOPHILA MERCATORUM
Authors: Ikeda Hiroshi , Carson Hampton L
Published: January 2021

A diploid parthenogenetic strain of Drosophila mercatorum was outcrossed to produce genetic variance among the impaternate female offspring. Selection experiments were carried out for reluctance of the parthenogenetic females to mate.

After only two cycles of selection, a parthenogenetic strain which is significantly less receptive to males from three different bisexual strains was obtained. It was also found that there is some degree of sexual isolation among the three bisexual strains used. The results support the idea that selection can render a newly produced diploid parthenogenetic strain behaviorally different from its bisexual ancestor. This appears to provide a framework which can explain the natural coexistence of diploid bisexual and diploid parthenogenetic biotypes in some species of insects.
KINETICS OF GENETIC RECOMBINATION IN ESCHERICHIA COLI K-12: COMPETITION BETWEEN GENETIC INTEGRATION AND DEGRADATION
Authors: Ou Jonathan T , Wood Thomas H
Published: January 2021

The effect of shifting zygotes from a rich medium into a poor medium (shift-down) on the frequency of recombination has been examined; our results suggest that protein syntheses other than those required for growth may be involved. Experiments with chloramphenicol support this notion, and further suggest that there is a competition between genetic integration and degradation in the recipient cells. By inhibiting protein synthesis one can shift the competition in favor of either integration or segregation, depending on the physiological state of the zygotes. By calculating the time required for segregation as one generation, we conclude that the recombination chromosome is homozygous at the time of integration.
ACID PHOSPHATASE MUTANTS IN CHLAMYDOMONAS: ISOLATION AND CHARACTERIZATION BY BIOCHEMICAL, ELECTROPHORETIC AND GENETIC ANALYSIS
Authors: Loppes R , Matagne R E
Published: January 2021

In order to isolate acid phosphatase mutants in the green alga Chlamydomonas reinhardi, a staining method for detecting the enzyme activity in colonies has been developed. The occurrence of more than one acid phosphatase brought about some difficulty in the selection of mutants. We have, however, found an original method of selection based on the differential heat sensitivity of the enzymes. After treatment of the wild-type strain with N-methyl-N'-nitro-N-nitrosoguanidine, two types of mutants were recovered, then analyzed by biochemical and electrophoretic methods. In the first class of mutants (P1, P2, P3,…) a heat-stable acid phosphatase bound to cellular debris of the crude extract was missing. The mutant Pa, representing the second class of mutations, was lacking a soluble heat-sensitive enzyme. These mutations were genetically different and exhibited mendelian inheritance.
THE SUPPRESSION OF AD-3B MUTANTS BY SUPERSUPPRESSORS IN NEUROSPORA CRASSA
Authors: Newcombe K D , Griffiths A J F
Published: January 2021

The action of eight suppersuppressors has been tested on 76 ad-3B mutants which were induced by base-pair transition mutagens. Thirteen mutants were found to be suppressible by at least one ssu gene. Most of the suppressible mutants were found to belong to a class in which one would expect to find nonsense mutants (polar complementing or noncomplementing classes, with AT at the mutant site). However, suppression was observed in other classes, including those containing presumed missense mutants. The specificity of the suppressors and the criteria for molecular classification of the mutants are discussed.
MUTATION INDUCTION IN THE MALE RECOMBINATION STRAINS OF DROSOPHILA MELANOGASTER
Authors: Slatko Barton E , Hiraizumi Yuichiro
Published: January 2021

One group of the second chromosome lines isolated from a southern Texas population of Drosophila melanogaster, which has been known to show relatively high frequencies of male recombinations, was found to increase the frequency of sex-linked recessive lethal mutations from a control frequency of 0.18% to 1.63%. The second group, which showed a very much reduced frequency of male recombinations, was found to cause a slight increase to 0.48%, although it was not statistically significant. The first group was also tested for the recessive lethal mutation frequency in the second chromosome; the frequency increased from a control frequency of 0.28% to 2.82%. Mapping of a portion of the sex-linked lethals indicated a distribution along the entire X chromosome, although there was a tendency of clustering towards the tip of the X chromosome. One sex-linked lethal line so far tested was found to be associated with an inversion (approximate breakpoints, 14A–18A). It was suggested that the element causing male recombination might be similar to the hi mutator gene studied earlier by Ives (1950).
THE GENETIC DIVERGENCE OF SUBLINES AS ASSESSED BY HISTOCOMPATIBILITY TESTING
Authors: Silvers Willys K , Gasser David L
Published: January 2021

The degree of genetic divergence which has occurred between a number of inbred strains of mice and between two sublines of inbred rats was assessed by determining the fate of inter-subline skin grafts. Sublines which had been separated for 29 and 42 generations possessed no detectable incompatibility, while three combinations of sublines judged to have been maintained apart for from 123 to 129 generations showed slight degrees of histoincompatibility. One pair of sublines which had been separated for 119 generations demonstrated a marked degree of incompatibility, and an F2 test suggested that mutations had occurred at four or five histocompatibility loci.
LIMITING DISTRIBUTION UNDER ASSORTATIVE MATING
Authors: Ghai G L
Published: January 2021

A multi-locus model for complete positive assortative mating is discussed. For a two-locus model, if the gene frequencies for the two loci are different, as they are likely to be, it is shown that in equilibrium the population is not composed of only two homozygous types, as is usually thought. The limiting distribution will have three homozygous genotypes depending upon the initial gene frequencies. If there are m-loci such that gene frequencies at all loci are different, there will be (m+1) such homozygous genotypes present in the equilibrium population, one in each phenotypic group.
SELECTION IN COMPLEX GENETIC SYSTEMS I. THE SYMMETRIC EQUILIBRIA OF THE THREE-LOCUS SYMMETRIC VIABILITY MODEL
Authors: Feldman Marcus W , Franklin Ian , Thomson Glenys J
Published: January 2021

The symmetric equilibria of the three-locus symmetric viability model are determined and their stability analyzed. For tight linkage there may be four stable equilibria, each characterized by having one pair of complementary chromosomes in high frequencies, with all others low. For looser linkage the only stable symmetric equilibrium is that with complete linkage equilibrium. For intermediate recombination values both types of equilibria may be stable. A new class of equilibria with all pairwise linkage disequilibria zero, but with third order linkage disequilibrium, has been discovered. It may be stable for tight linkage.
A NEW MUTANT CONTROLLING MITOTIC CHROMOSOME DISJUNCTION IN DROSOPHILA MELANOGASTER
Authors: Gelbart William M
Published: January 2021

A new mutant, mit (mitotic loss inducer), is described. The mutant is recessive and maternal in action, producing gynandromorphs and haplo-4 mosaics among the progeny of homozygous mit females. Mosaic loss of maternal or paternal chromosomes can occur. The probabilities of either maternal or paternal X chromosome loss are equal. mit has been mapped to approximately 57 on the standard X chromosome map.—Using gyandromorphs generated by mit, a morphogenetic fate map, placing the origins of 40 cuticular structures on the blastoderm surface, has been constructed. This fate map is consistent with embryological data and with the two other fate maps generated in different ways.
GENETIC ANALYSIS OF DUPLICATE MALATE DEHYDROGENASE LOCI IN THE PINK SALMON, ONCORHYNCHUS GORBUSCHA
Authors: Aspinwall Nevin
Published: January 2021

The results of breeding experiments with the pink salmon, Oncorhynchus gorbuscha, indicate that s-MDH-A and s-MDH-B subunits are each encoded by duplicate loci. Limited evidence suggests also that the two loci encoding for the s-MDH-A subunit are each polymorphic and linked or pseudolinked.
AN ELECTROPHORETICALLY SILENT POLYMORPHISM FOR THE BETA CHAINS OF RABBIT HEMOGLOBIN AND ASSOCIATED POLYRIBOSOME PATTERNS
Authors: Garrick Michael D , Bricker J , Garrick Laura M
Published: January 2021

The β chain of rabbit (Oryctolagus caniculus) hemoglobin has previously been reported to contain a single residue of isoleucine at β112. We have detected other rabbits with either zero isoleucyl residues or half a residue per β chain. This character is polymorphic and inherited as a simple mendelian autosomal codominant.—Normally the modal number of ribosomes per polyribosome is 4 to 6 in reticulocyte lysates; but incubation of rabbit reticulocytes prior to lysis with L-o-methylthreonine (OMT), an isostere of isoleucine, leads to a bimodal distribution in lysates with 2–3 and 8–12 ribosomes as modes. This alteration has been attributed to ribosomal traffic jams caused by starvation for ile-tRNA at mRNA codons corresponding to the locations of isoleucyl residues at positions α10, α17, α55 and β112. We have confirmed this interpretation by incubating OMT with reticulocytes from rabbits with integral, half integral and nil values for isoleucyl residues per β chain to show that formation of the larger clusters of polyribosomes requires that β112 = ile.
GENETIC ANALYSIS OF AN ESCHERICHIA COLI MUTANT WITH A LESION IN STABLE RNA TURNOVER
Authors: Ohnishi Yoshinari
Published: January 2021

A mutant that rapidly degrades more than 80% of its rRNA and tRNA under defined conditions was genetically analyzed. Two genes, srnA and srnB, are separately located, and the mutated alleles of both are required for degradation of stable RNA in cultures treated with rifampicin at 42°. srnA is closely linked to tsx by matings and transduction tests; by P1 transduction, the gene order is lac (9 min) proC (9.55 min) tsx (9.8 min) srnA (about 10 min) purE (12 min) rnsA (14.4 min). srnB is not yet completely mapped, but is outside the lac-rnsA region, probably in the region between 75 and 90 min.—The product of the rnsA gene, RNase I, is a potent endonuclease of E. coli, and the only one known that can attack ribosomes and tRNA. However, not only are the srn lesions genetically separate from rnsA, but also, derivatives of an srn strain were prepared lacking RNase I, and they retain the Srn- phenotype. Thus, no correlation of rapid RNA turnover and RNase I activity has been found.
MITOCHONDRIAL GENETICS. VI THE PETITE MUTATION IN SACCHAROMYCES CEREVISIAE: INTERRELATIONS BETWEEN THE LOSS OF THE ρ+ FACTOR AND THE LOSS OF THE DRUG RESISTANCE MITOCHONDRIAL GENETIC MARKERS
Authors: Deutsch J , Dujon B , Netter P , Petrochilo E , Slonimski P P , Bolotin-Fukuhara M , Coen D
Published: January 2021

The survival of the ρ+ factor and of DrugR mitochondrial genetic markers after exposure to ethidium bromide has been studied. A technique allowing the determination of DrugR genetic markers among a great number of both grande and petite colonies has been developed. The results have been analyzed by the target theory. The survival of the ρ+ factor is always less than the survival of any DrugR genetic marker. The survivals of CR and ER are similar to each other, while that of OR is greater than that of the other two DrugR markers. All possible combinations of DrugR markers have been found among the ρ- petite cells induced, while the only type found among the grande colonies is the preexisting one. The loss of the CR and ER genetic markers was found to be the most frequently concomitant, while the correlation between the loss of the OR marker and the other two DrugR markers is less strong. Similar results have been obtained after U.V. irradiation. Interpretations concerning the structure of the yeast mitochondrial genome are given and hypotheses on the mechanism of petite mutation discussed.
PREFERENTIAL ASCUS DISCHARGE DURING CROSS MATURATION IN SORDARIA BREVICOLLIS
Authors: MacDonald D J , Bond D J
Published: January 2021

Crosses involving spore color mutants of Sordaria brevicollis all showed a decline in the frequency of second division asymmetric asci (2:2:2:2's) as the cross matured. This decline was due to the preferential maturation and/or discharge of these asci. The proportion of spindle overlap and recombinational asci within the group did not change as shown by ascus dissection. The preferential discharge was also found to occur in two-point crosses where the asci did not contain wild-type spores.
MUTATIONS AFFECTING SEXUAL CONJUGATION AND RELATED PROCESSES IN SACCHAROMYCES CEREVISIAE. II. GENETIC ANALYSIS OF NONMATING MUTANTS
Authors: Mackay Vivian , Manney Thomas R
Published: January 2021

Rare diploids formed by sterile mutants have been studied by tetrad analysis. Sixteen classes of mutants representing at least five distinct genetic loci have been defined. One group of mutations, isolated only in α, maps at the mating-type locus, while none of the others shows any linkage to mating type. Some of the mutations are nonspecific for mating type, while others act only on a or α. In addition, mutations were found that prevent sporulation when heterozygous in diploids. These appear to be mutations of the mating-type alleles.
MORTALITY IN THE CHILDREN OF ATOMIC BOMB SURVIVORS AND CONTROLS
Authors: Neel James V , Kato Hiroo , Schull William J
Published: January 2021

A continuing study of mortality rates among children born to survivors of the atomic bombings and a suitable group of controls has been updated; the average interval between birth and verification of death or survival is 17 years. The mortality experience is now based on 18,946 children liveborn to parents one or both of whom were proximally exposed, receiving jointly an estimated dose of 117 rem; 16,516 children born to distally exposed parents receiving essentially no radiation; and 17,263 children born to parents not in Hiroshima or Nagasaki at the time of the bombings. No clearly significant effect of parental exposure on child's survival can be demonstrated either by a contingency χ2 type of analysis or regression analysis. On the basis of the regression data, the minimal gametic doubling dose of radiation of this type for mutations resulting in death during (on the average) the first 17 years of life among liveborn infants conceived 0–13 years after parental exposure is estimated at 46 rem for fathers and 125 rem for mothers. On the basis of experimental data, the gametic doubling dose for chronic, low-level radiation would be expected to be three to four times this value for males and as much as 1000 rem for females.
A MARKOV PROCESS OF GENE FREQUENCY CHANGE IN A GEOGRAPHICALLY STRUCTURED POPULATION
Authors: Maruyama Takeo
Published: January 2021

A Markov process (chain) of gene frequency change is derived for a geographically-structured model of a population. The population consists of colonies which are connected by migration. Selection operates in each colony independently. It is shown that there exists a stochastic clock that transforms the originally complicated process of gene frequency change to a random walk which is independent of the geographical structure of the population. The time parameter is a local random time that is dependent on the sample path. In fact, if the alleles are selectively neutral, the time parameter is exactly equal to the sum of the average local genetic variation appearing in the population, and otherwise they are approximately equal. The Kolmogorov forward and backward equations of the process are obtained. As a limit of large population size, a diffusion process is derived. The transition probabilities of the Markov chain and of the diffusion process are obtained explicitly. Certain quantities of biological interest are shown to be independent of the population structure. The quantities are the fixation probability of a mutant, the sum of the average local genetic variation and the variation summed over the generations in which the gene frequency in the whole population assumes a specified value.
ON RECOMBINATION-DEFECTIVE MEIOTIC MUTANTS IN DROSOPHILA MELANOGASTER
Authors: Carpenter Adelaide T C , Sandler L
Published: January 2021

The genetic effects of four recombination-defective meiotic mutants in D. melanogaster on recombination, segregation and the relationship between the two have been examined. The results suggest the following. (1) The anomalous meiotic segregation observed in females carrying recombination-defective meiotic mutants is a normal consequence of the reduction in exchange; each recombination-defective mutant can, therefore, be defined by a single lesion in the control of recombination. (2) Of the operations used to date to characterize this lesion, the most informative is whether the decrease in recombination is uniform along the chromosome arm or nonuniform; in particular, if the formation of recombinants is visualized as a two-step process consisting of the establishment of possible exchange points (exchange preconditions) followed by exchange itself, then mutants that uniformly decrease crossing over involve defects in the second step while mutants that result in a nonuniform decrease involve defects in the establishment of exchange preconditions. (3) Of the fourteen loci identified by recombination-defective meiotic mutants, only one (with two alleles) is involved in exchange itself; the others all reduce recombination most drastically in distal regions, suggesting that the establishment of exchange preconditions involves polar processes. (4) A very general description of the polar establishment of exchange preconditions is presented; this description has the property that if a precondition meiotic mutant affects interference, the coefficient of coincidence will be increased in proportion to the decrease in recombination which is what is observed for all recombination-defective meiotic mutants studied to date.
A COLD-SENSITIVE ZYGOTIC LETHAL CAUSING HIGH FREQUENCIES OF NONDISJUNCTION DURING MEIOSIS I IN DROSOPHILA MELANOGASTER FEMALES
Authors: Wright Theodore R F
Published: January 2021

The X-linked, cold-sensitive zygotic lethal, l(1)TW-6cs, both in homozygous and heterozygous females, induces nondisjunction of all four chromosomes at Meiosis I at both 25° and 17°. Nondisjunction frequencies approaching 0.5 for the X and fourth chromosomes have been observed at 16°–18°. The disjunction of the X chromosomes in males is not affected. The mutant causes mitotic irregularities in zygotes at both 25° and 17°. Mortality of all zygotes produced by the crosses 6cs/6cs × 6cs/BsY and FM7/6cs × 6cs/BsY is respectively 86% and 67–74% at 25° and 99.8–99.9% and 94% at 17°. The mortality of 6cs hemizygotes derived from females carrying no doses of 6cs (C(1)DX,y f/y × 6cs/BsY) is 45–55% at 25° and 98% at 17°. The length of the temperature-sensitive period for 6cs homo- and hemizygotes is affected by the maternal dosage of 6cs; the shortest TSP is for zero and the longest is for two maternal doses. Mortality takes place primarily during embryogenesis with some larval and little pupal mortality. Analysis of sectioned embryos indicates that the large array of different patterns of damage observed could have arisen from abnormal cleavage divisions and the incomplete population of the blastoderm with nuclei.
SELECTION FOR BLOOD PRESSURE LEVELS IN MICE
Authors: Schlager Gunther
Published: January 2021

Response to two-way selection for systolic blood pressure was immediate and continuous for about eight generations. In the twelfth generation, the High males differed from the Low males by 38 mmHG; the females differed by 39 mmHg. There was little overlap between the two lines and they were statistically significant from each other and from the Random control line. There appeared to be no more additive genetic variance in the eleventh and twelfth generations. Causes for the cessation of response are explored. This is probably due to a combination of natural selection acting to reduce litter sizes in the Low line, a higher incidence of sudden deaths in the High line, and loss of favorable alleles as both selection lines went through a population bottleneck in the ninth generation.—In the eleventh generation, the selected lines were used to produce F1, F2, and backcross generations. A genetic analysis yielded significant additive and dominance components in the inheritance of systolic blood pressure.
LIKELIHOOD ANALYSIS OF RECOMBINATIONAL DISEQUILIBRIUM IN MULTIPLE-LOCUS GAMETIC FREQUENCIES
Authors: Smouse Peter E
Published: January 2021

Likelihood methods are developed for the estimation and testing of multiple-locus gametic disequilibria, using log-linear models of parametric effects. The estimates of disquilibrium are related to Kimura's Z-measure, and may be extended to multiple alleles and multiple loci. Likelihood ratio test criteria are constructed, which are asymptotically distributed as χ2. The analysis is partitioned into various components corresponding to two-locus, residual three-locus, and higher order disequilibria. A four-locus example from Hordeum vulgare L. is utilized to illustrate the analysis. Most of the multiple-locus disequilibrium is accounted for by two-locus effects, and closely linked loci show considerably more disequilibrium than unlinked loci. It is shown that all possible pairwise comparisons are not statistically independent.
COVARIANCES BETWEEN ARBITRARY RELATIVES IN AUTOTETRAPLOIDS WITH PANMICTIC DISEQUILIBRIUM
Authors: Gallais A
Published: January 2021

In random mating autopolyploid populations which have not reached equilibrium, two alleles may be interdependent as a result of the phenomenon of gametic recombination, i.e. the maintenance through successive gamete generations of an association of two alleles from the same gamete in a source reference generation. Any two alleles are dependent by this relationship if they derive by descent from the same ancestral gamete in the source population. Applied with the classical notion of identity by descent, the concept thus defined identifies new coefficients of dependence between arbitrary relatives. Coefficients of dependence are probabilities attached to the drawing of genes from two zygotes such that there are certain relationships amongst them. Applying the concept to autotetraploids, consideration of the states of dependence between the genes of a zygote or of a pair of zygotes leads to the definition of new parameters bearing on population means, variances and covariances, for arbitrary inbreeding. The absence of epistasis is supposed. Some applications of interest in artificial selection are briefly envisaged, with simplifying restrictions on genetic effects. The particular case of diallelism is also considered.
A new duck genome reveals conserved and convergently evolved chromosome architectures of birds and mammals
Authors: Li Jing , Zhang Jilin , Liu Jing , Zhou Yang , Cai Cheng , Xu Luohao , Dai Xuelei , Feng Shaohong , Guo Chunxue , Rao Jinpeng , Wei Kai , Jarvis Erich D , Jiang Yu , Zhou Zhengkui , Zhang Guojie , Zhou Qi
Published: January 2021

Background

Ducks have a typical avian karyotype that consists of macro- and microchromosomes, but a pair of much less differentiated ZW sex chromosomes compared to chickens. To elucidate the evolution of chromosome architectures between ducks and chickens, and between birds and mammals, we produced a nearly complete chromosomal assembly of a female Pekin duck by combining long-read sequencing and multiplatform scaffolding techniques.

Results

A major improvement of genome assembly and annotation quality resulted from the successful resolution of lineage-specific propagated repeats that fragmented the previous Illumina-based assembly. We found that the duck topologically associated domains (TAD) are demarcated by putative binding sites of the insulator protein CTCF, housekeeping genes, or transitions of active/inactive chromatin compartments, indicating conserved mechanisms of spatial chromosome folding with mammals. There are extensive overlaps of TAD boundaries between duck and chicken, and also between the TAD boundaries and chromosome inversion breakpoints. This suggests strong natural selection pressure on maintaining regulatory domain integrity, or vulnerability of TAD boundaries to DNA double-strand breaks. The duck W chromosome retains 2.5-fold more genes relative to chicken. Similar to the independently evolved human Y chromosome, the duck W evolved massive dispersed palindromic structures, and a pattern of sequence divergence with the Z chromosome that reflects stepwise suppression of homologous recombination.

Conclusions

Our results provide novel insights into the conserved and convergently evolved chromosome features of birds and mammals, and also importantly add to the genomic resources for poultry studies.
Differentiation of glioblastoma stem cells promoted by miR-128 or miR-302a overexpression enhances senescence-associated cytotoxicity of axitinib
Authors: Cardoso Ana M , Morais Catarina M , Pena Frederico , Marante Tânia , Cunha Pedro P , Jurado Amália S , Pedroso de Lima Maria C
Published: January 2021

Despite the intense global efforts towards an effective treatment of glioblastoma (GB), current therapeutic options are unsatisfactory with a median survival time of 12–15 months after diagnosis, which has not improved significantly over more than a decade. The high tumoral heterogeneity confers resistance to therapies, which has hindered a successful clinical outcome, GB remaining among the deadliest cancers. A hallmark of GB is its high recurrence rate, which has been attributed to the presence of a small subpopulation of tumor cells called GB stem-like cells (GSC). In the present work, the efficacy of a multimodal strategy combining microRNA (miRNA) modulation with new generation multitargeted tyrosine kinase inhibitors (imatinib and axitinib) was investigated aiming at tackling this subpopulation of GB cells. MiR-128 and miR-302a were selected as attractive therapeutic candidates on the basis of previous findings reporting that reestablishment of their decreased expression levels in GSC resulted in cell differentiation, which could represent a possible strategy to sensitize GSC to chemotherapy. Our results show that overexpression of miR-128 or miR-302a induced GSC differentiation, which enhanced senescence mediated by axitinib treatment, thus further impairing GSC proliferation. We also provided evidence for the capacity of GSC to efficiently internalize functionalized stable nucleic acid lipid particles, previously developed and successfully applied in our laboratory to target GB. Taken together, our findings will be important in the future design of a GB-targeted multimodal miRNA-based gene therapy, combining overexpression of miR-128 or miR-302a with axitinib treatment, endowed with the ability to overcome drug resistance.
Biological Activity of trans-2-Hexenal Against the Storage Insect Pest Tribolium castaneum (Coleoptera: Tenebrionidae) and Mycotoxigenic Storage Fungi
Authors: Cui Kaidi , He Leiming , Cui Guangrui , Zhang Tao , Chen Yue , Zhang Tao , Mu Wei , Liu Feng
Published: January 2021

Grain commodities in postharvest storage often deteriorate because of fungal and insect attacks. With the green consumption requirements of consumers, ecofriendly and safe pesticides are needed for grain storage. The current study investigated the efficacy of the plant volatile compound trans-2-hexenal against the storage insect pest Tribolium castaneum (Herbst) and three commonly occurring storage fungi, viz., Fusarium graminearum, Aspergillus flavus, and Aspergillus niger, to recommend its application as a botanical fumigant for grain commodities. trans-2-Hexenal weakly repels T. castaneum but has favorable insecticidal activity against multiple developmental stages of T. castaneum, ranging in sensitivity as follows: eggs (LC50 = 14.3 µl/l) > adults (31.6 µl/l) > young larvae (42.1 µl/l) > mature larvae (64.5 µl/l) > pupae (70.5 µl/l). Moreover, trans-2-hexenal caused a high malformation rate and high mortality in adults developed from fumigated pupae. In a 7-d grain, trans-2-hexenal at 0.8 µl/ml provided an appreciable efficacy (81.3%), and concentrations ≥ 0.1 µl/ml completely inhibited the offspring of T. castaneum. trans-2-Hexenal was nonphytotoxic to the seed germination and seedling growth of wheat seeds. Furthermore, trans-2-hexenal completely inhibited the growth of A. flavus, F. graminearum, and A. niger at 5, 10, and 10 µl/l, respectively. The favorable biological activity of trans-2-hexenal against T. castaneum and three frequently occurring mycotoxigenic storage fungi indicated the potential of trans-2-hexenal for simultaneously controlling pests and pathogens, which could reduce its application frequency in grains and decrease pesticide resistance risks.