bluuebunny/crossref_metadata_2025 huggingface dataset:
Short-course radiotherapy with consolidation chemotherapy versus conventionally fractionated long-course chemoradiotherapy for locally advanced rectal cancer: randomized clinical trial
Authors: Chakrabarti D , Rajan S , Akhtar N , Qayoom S , Gupta S , Verma M , Srivastava K , Kumar V , Bhatt M L B , Gupta R
Published: January 2021

Background

The trial hypothesis was that, in a resource-constrained situation, short-course radiotherapy would improve treatment compliance compared with conventional chemoradiotherapy for locally advanced rectal cancer, without compromising oncological outcomes.

Methods

In this open-label RCT, patients with cT3, cT4 or node-positive non-metastatic rectal cancer were allocated randomly to 5 × 5 Gy radiotherapy and two cycles of XELOX (arm A) or chemoradiotherapy with concurrent capecitabine (arm B), followed by total mesorectal excision in both arms. All patients received a further six cycles of adjuvant chemotherapy with the XELOX regimen. The primary endpoint was treatment compliance, defined as the ability to complete planned treatment, including neoadjuvant radiochemotherapy, surgery, and adjuvant chemotherapy to a dose of six cycles.

Results

Of 162 allocated patients, 140 were eligible for analysis: 69 in arm A and 71 in arm B. Compliance with planned treatment (primary endpoint) was greater in arm A (63 versus 41 per cent; P = 0.005). The incidence of acute toxicities of neoadjuvant therapy was similar (haematological: 28 versus 32 per cent, P = 0.533; gastrointestinal: 14 versus 21 per cent, P = 0.305; grade III–IV: 2 versus 4 per cent, P = 1.000). Delays in radiotherapy were less common in arm A (9 versus 45 per cent; P < 0.001), and overall times for completion of neoadjuvant treatment were shorter (P < 0.001). The rates of R0 resection (87 versus 90 per cent; P = 0.554), sphincter preservation (32 versus 35 per cent; P = 0.708), pathological complete response (12 versus 10 per cent; P = 0.740), and overall tumour downstaging (75 versus 75 per cent; P = 0.920) were similar. Downstaging of the primary tumour (ypT) was more common in arm A (P = 0.044). There was no difference in postoperative complications between trial arms (P = 0.838).

Conclusion

Reduced treatment delays and a higher rate of compliance were observed with treatment for short-course radiotherapy with consolidation chemotherapy, with no difference in early oncological surgical outcomes. In time- and resource-constrained rectal cancer units in developing countries, short-course radiotherapy should be the standard of care.
Complex evolutionary history of two ecologically significant grass genera,ThemedaandHeteropogon(Poaceae: Panicoideae: Andropogoneae)
Authors: Arthan Watchara , Dunning Luke T , Besnard Guillaume , Manzi Sophie , Kellogg Elizabeth A , Hackel Jan , Lehmann Caroline E R , Mitchley Jonathan , Vorontsova Maria S
Published: January 2021

Themeda and Heteropogon are closely related grass genera frequently dominant in tropical C4 grasslands. Relationships between them are poorly resolved, impeding ecological study, especially of T. triandra with a broad distribution from Africa to East Asia, and H. contortus with a pantropical distribution. Our analyses of plastome and nuclear genomes with comprehensive sampling of Themeda and Heteropogon demonstrate that neither genus is monophyletic as currently circumscribed. Plastome and nuclear data place H. melanocarpus and H. ritchiei in Themeda. Nested in T. triandra are T. quadrivalvis and T. unica, demonstrating that this widespread species is more morphologically diverse than previously recognized. Heteropogon fischerianus is nested in H. contortus. The picture is more complex for H. triticeus that is sister to H. contortus in the nuclear analysis and to Cymbopogon in the plastome analysis. This incongruence between nuclear and plastid phylogenetic trees suggests hybridization between Cymbopogon-related genome donors and H. contortus. Plastome dating estimates the Themeda–Heteropogon crown age at c. 7.6 Myr, consistent with the Miocene C4 grassland expansion. Themeda triandra and H. contortus diversified 1–2 Mya in the Pleistocene. These results establish a foundation for studying the history of these ecologically significant widespread grasses and the ecosystems they form.
Creative Destruction: A Basic Computational Model of Cortical Layer Formation
Authors: Bauer Roman , Clowry Gavin J , Kaiser Marcus
Published: January 2021

One of the most characteristic properties of many vertebrate neural systems is the layered organization of different cell types. This cytoarchitecture exists in the cortex, the retina, the hippocampus, and many other parts of the central nervous system. The developmental mechanisms of neural layer formation have been subject to substantial experimental efforts. Here, we provide a general computational model for cortical layer formation in 3D physical space. We show that this multiscale, agent-based model, comprising two distinct stages of apoptosis, can account for the wide range of neuronal numbers encountered in different cortical areas and species. Our results demonstrate the phenotypic richness of a basic state diagram structure. Importantly, apoptosis allows for changing the thickness of one layer without automatically affecting other layers. Therefore, apoptosis increases the flexibility for evolutionary change in layer architecture. Notably, slightly changed gene regulatory dynamics recapitulate the characteristic properties observed in neurodevelopmental diseases. Overall, we propose a novel computational model using gene-type rules, exhibiting many characteristics of normal and pathological cortical development.
Neural Basis of Biased Competition in Development: Sensory Competition in Visual Cortex of School-Aged Children
Authors: Kim Na Yeon , Pinsk Mark A , Kastner Sabine
Published: January 2021

The fundamental receptive field (RF) architecture in human visual cortex becomes adult-like by age 5. However, visuo-spatial functions continue to develop until teenage years. This suggests that, despite the early maturation of the RF structure, functional interactions within and across RFs may mature slowly. Here, we used fMRI to investigate functional interactions among multiple stimuli in the visual cortex of school children (ages 8 to 12) in the context of biased competition theory. In the adult visual system, multiple objects presented in the same visual field compete for neural representation. These competitive interactions occur at the level of the RF and are therefore closely linked to the RF architecture. Like in adults, we found suppression of evoked responses in children’s visual cortex when multiple stimuli were presented simultaneously. Such suppression effects were modulated by the spatial distance between the stimuli as a function of RF size across the visual system. Our findings suggest that basic competitive interactions in the visual cortex of children above age 8 operate in an adult-like manner, with subtle differences in early visual areas and area MT. Our study establishes a paradigm and provides baseline data to investigate the neural basis of visuo-spatial processing in typical and atypical development.
Data Science-Based Analysis of Patient Subgroup Structures Suggest Effects of Rhinitis on All Chemosensory Perceptions in the Upper Airways
Authors: Lötsch Jörn , Hummel Thomas
Published: January 2021

Viral rhinitis contributes significantly to olfactory dysfunction, but it is unclear how many patients have other chemosensory symptoms in addition to olfactory loss. This was addressed in the present reanalysis of data previously published in Pellegrino R, Walliczek-Dworschak U, Winter G, Hull D, Hummel T. 2017. Investigation of chemosensitivity during and after an acute cold. Int Forum Allergy Rhinol. 7(2):185–191, using unsupervised and supervised machine-learning methods. Fifty-eight patients with acute rhinitis and 59 healthy controls were assessed for orthonasal and retronasal olfactory function, taste, and intranasal trigeminal sensitivity. Unsupervised analysis showed that during rhinitis, clinical scores of olfactory function, expressed as threshold, discrimination, identification (TDI) values, were trimodally distributed. Two minor modes were separated from the main mode at TDI = 30.5, which corresponds to the established limit of hyposmia. This trimodal distribution was not observed after the rhinitis subsided. Olfactory function was not significantly impaired in 40% of all rhinitis patients, whereas it was transiently impaired in 59%. For this group, supervised machine-learning algorithms could be trained with information on retronasal olfactory function, gustatory function, and trigeminal sensitivity to assign patients to subgroups based on orthonasal olfactory function with a balanced classification accuracy of 64–65%. The ability to recognize patients with olfactory loss based on retronasal olfactory function as well as gustatory function and trigeminal sensitivity suggests in turn that these modalities are affected by rhinitis. However, the only modest accuracy at which this information allowed to reproduce the olfactory diagnosis indicated they are involved in the symptomatology of rhinitis to a lesser extent compared with the orthonasal olfactory function.
Antigen-Based Testing but Not Real-Time Polymerase Chain Reaction Correlates With Severe Acute Respiratory Syndrome Coronavirus 2 Viral Culture
Authors: Pekosz Andrew , Parvu Valentin , Li Maggie , Andrews Jeffrey C , Manabe Yukari C , Kodsi Salma , Gary Devin S , Roger-Dalbert Celine , Leitch Jeffry , Cooper Charles K
Published: January 2021

Background

Individuals can test positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by molecular assays following the resolution of their clinical disease. Recent studies indicate that SARS-CoV-2 antigen–based tests are likely to be positive early in the disease course, when there is an increased likelihood of high levels of infectious virus.

Methods

Upper respiratory specimens from 251 participants with coronavirus disease 2019 symptoms (≤7 days from symptom onset) were prospectively collected and tested with a lateral flow antigen test and a real-time polymerase chain reaction (rt-PCR) assay for detection of SARS-CoV-2. Specimens from a subset of the study specimens were utilized to determine the presence of infectious virus in the VeroE6TMPRSS2 cell culture model.

Results

The antigen test demonstrated a higher positive predictive value (90%) than rt-PCR (70%) when compared to culture-positive results. The positive percentage agreement for detection of infectious virus for the antigen test was similar to rt-PCR when compared to culture results.

Conclusions

The correlation between SARS-CoV-2 antigen and SARS-CoV-2 culture positivity represents a significant advancement in determining the risk for potential transmissibility beyond that which can be achieved by detection of SARS-CoV-2 genomic RNA. SARS-CoV-2 antigen testing can facilitate low-cost, scalable, and rapid time-to-result, while providing good risk determination of those who are likely harboring infectious virus, compared to rt-PCR.
Pathology of COVID-19-associated acute kidney injury
Authors: Sharma Purva , Ng Jia H , Bijol Vanesa , Jhaveri Kenar D , Wanchoo Rimda
Published: January 2021

Acute kidney injury (AKI) is common among hospitalized patients with coronavirus disease 2019 (COVID-19), with the occurrence of AKI ranging from 0.5% to 80%. An improved knowledge of the pathology of AKI in COVID-19 is crucial to mitigate and manage AKI and to improve the survival of patients who develop AKI during COVID-19. In this review, we summarize the published cases and case series of various kidney pathologies seen with COVID-19. Both live kidney biopsies and autopsy series suggest acute tubular injury as the most commonly encountered pathology. Collapsing glomerulopathy and thrombotic microangiopathy are other encountered pathologies noted in both live and autopsy tissues. Other rare findings such as anti-neutrophil cytoplasmic antibody vasculitis, anti-glomerular basement membrane disease and podocytopathies have been reported. Although direct viral infection of the kidney is possible, it is certainly not a common or even widespread finding reported at the time of this writing (November 2020).
Animal social networks: an introduction for complex systems scientists
Authors: Brask Josefine Bohr , Ellis Samuel , Croft Darren P
Published: January 2021

Many animals live in societies where individuals frequently interact socially with each other. The social structures of these systems can be studied in depth by means of network analysis. A large number of studies on animal social networks in many species have in recent years been carried out in the biological research field of animal behaviour and have provided new insights into behaviour, ecology and social evolution. This line of research is currently not so well connected to the field of complex systems as could be expected. The purpose of this article is to provide an introduction to animal social networks for complex systems scientists and highlight areas of synergy. We believe that an increased integration of animal social networks with the interdisciplinary field of complex systems, and networks would be beneficial for various reasons. Increased collaboration between researchers in this field and biologists studying animal social systems could be valuable in solving challenges that are of importance to animal social network research. Furthermore, animal social networks provide the opportunity to investigate hypotheses about complex systems across a range of natural real-world social systems. In this article, we describe what animal social networks are and main research themes where they are studied; we give an overview of the methods commonly used to study animal social networks; we highlight challenges in the study of animal social networks where complex systems expertise may be particularly valuable; and we consider aspects of animal social networks that may be of particular interest to complex systems researchers. We hope that this will help to facilitate further interdisciplinary collaborations involving animal social networks and further integration of these networks into the field of complex systems.
TNFα induces endothelial dysfunction in rheumatoid arthritis via LOX-1 and arginase 2: reversal by monoclonal TNFα antibodies
Authors: Akhmedov Alexander , Crucet Margot , Simic Branko , Kraler Simon , Bonetti Nicole R , Ospelt Caroline , Distler Oliver , Ciurea Adrian , Liberale Luca , Jauhiainen Matti , Metso Jari , Miranda Melroy , Cydecian Rose , Schwarz Lena , Fehr Vera , Zilinyi Rita , Amrollahi-Sharifabadi Mohammad , Ntari Lydia , Karagianni Niki , Ruschitzka Frank , Laaksonen Reijo , Vanhoutte Paul M , Kollias George , Camici Giovanni G , Lüscher Thomas F
Published: January 2021

Aims

Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting joints and blood vessels. Despite low levels of low-density lipoprotein cholesterol (LDL-C), RA patients exhibit endothelial dysfunction and are at increased risk of death from cardiovascular complications, but the molecular mechanism of action is unknown. We aimed in the present study to identify the molecular mechanism of endothelial dysfunction in a mouse model of RA and in patients with RA.

Methods and results

Endothelium-dependent relaxations to acetylcholine were reduced in aortae of two tumour necrosis factor alpha (TNFα) transgenic mouse lines with either mild (Tg3647) or severe (Tg197) forms of RA in a time- and severity-dependent fashion as assessed by organ chamber myograph. In Tg197, TNFα plasma levels were associated with severe endothelial dysfunction. LOX-1 receptor was markedly up-regulated leading to increased vascular oxLDL uptake and NFκB-mediated enhanced Arg2 expression via direct binding to its promoter resulting in reduced NO bioavailability and vascular cGMP levels as shown by ELISA and chromatin immunoprecipitation. Anti-TNFα treatment with infliximab normalized endothelial function together with LOX-1 and Arg2 serum levels in mice. In RA patients, soluble LOX-1 serum levels were also markedly increased and closely related to serum levels of C-reactive protein. Similarly, ARG2 serum levels were increased. Similarly, anti-TNFα treatment restored LOX-1 and ARG2 serum levels in RA patients.

Conclusions

Increased TNFα levels not only contribute to RA, but also to endothelial dysfunction by increasing vascular oxLDL content and activation of the LOX-1/NFκB/Arg2 pathway leading to reduced NO bioavailability and decreased cGMP levels. Anti-TNFα treatment improved both articular symptoms and endothelial function by reducing LOX-1, vascular oxLDL, and Arg2 levels.
ECCO Topical Review Optimising Reporting in Surgery, Endoscopy, and Histopathology
Authors: Adamina Michel , Feakins Roger , Iacucci Marietta , Spinelli Antonino , Cannatelli Rosanna , D’Hoore André , Driessen Ann , Katsanos Konstantinos , Mookhoek Aart , Myrelid Pär , Pellino Gianluca , Peros Georgios , Tontini Gian Eugenio , Tripathi Monika , Yanai Henit , Svrcek Magali
Published: January 2021

Background and Aims

Diagnosis and management of inflammatory bowel diseases [IBD] requires a lifelong multidisciplinary approach. The quality of medical reporting is crucial in this context. The present topical review addresses the need for optimised reporting in endoscopy, surgery, and histopathology.

Methods

A consensus expert panel consisting of gastroenterologists, surgeons, and pathologists, convened by the European Crohn’s and Colitis Organisation, performed a systematic literature review. The following topics were covered: in endoscopy: [i] general IBD endoscopy; [ii] disease activity and surveillance; [iii] endoscopy treatment in IBD; in surgery: [iv] medical history with surgical relevance, surgical indication, and strategy; [v] operative approach; [vi] intraoperative disease description; [vii] operative steps; in pathology: [viii] macroscopic assessment and interpretation of resection specimens; [ix] IBD histology, including biopsies, surgical resections, and neoplasia; [x] IBD histology conclusion and report. Statements were developed using a Delphi methodology incorporating two consecutive rounds. Current practice positions were set when ≥ 80% of participants agreed on a recommendation.

Results

Thirty practice positions established a standard terminology for optimal reporting in endoscopy, surgery, and histopathology. Assessment of disease activity, surveillance recommendations, advice to surgeons for operative indication and strategies, including margins and extent of resection, and diagnostic criteria of IBD, as well as guidance for the interpretation of dysplasia and cancer, were handled. A standardised report including a core set of items to include in each specialty report, was defined.

Conclusions

Interdisciplinary high-quality care requires thorough and standardised reporting across specialties. This topical review offers an actionable framework and practice recommendations to optimise reporting in endoscopy, surgery, and histopathology.
Results of two different echocardiography-guided approaches to closure of perimembranous ventricular septal defects
Authors: Bu Haisong , Yang Yifeng , Wu Qin , Hu Shijun , Jin Wancun , Gong Xueyang , Zhao Tianli
Published: January 2021

OBJECTIVES

The feasibility of mini-invasive closure of perimembranous ventricular septal defects has been proven, but can cause surgical incision or sternum injury. A relevant but, to date, unanswered question is whether there exists a treatment without surgical trauma, radiation exposure and arterial complications.

METHODS

From May 2017 to January 2020, a total of 449 patients with perimembranous ventricular septal defect [mean age 5.0 ± 6.1 years (range 0.8–52.0 years)] were involved in this study and underwent 2 different echocardiography-guided operative procedures [percutaneous device closure (group A) or percardiac device closure (group B)] based on the patients’ or their parents’ choice. The clinical data were collected and a retrospective analysis was performed.

RESULTS

Fifty-five (96.5%) cases were successfully occluded in group A, and 2 (3.5%) patients were converted to percardiac device closure; 379 (96.7%) patients in group B underwent percardiac device closure, and 13 patients (3.3%) were turned to open-heart surgery after occlusion procedure failure. There were statistically significant differences (P < 0.05) between the 2 groups in operation time, postoperative hospitalization time and blood transfusion requirement. No acute complications or severe adverse events (death, valve injury, complete atrioventricular block and embolism) occurred either in the early period or during the follow-up.

CONCLUSIONS

Percutaneous device closure can achieve the same validity and safety as percardiac device closure for treating perimembranous ventricular septal defects with a more rapid recovery and less trauma.
Are 18F-fluorodeoxyglucose positron emission tomography results reliable in patients with ascending aortic grafts? A prospective study in non-infected patients
Authors: Martínez-López Daniel , Rodríguez Alfonso Begoña , Ramos Martínez Antonio , Martín López Carlos Esteban , de Villarreal Soto Juan Esteban , Ríos Rosado Elsa Carolina , Villar García Susana , Ospina Mosquera Víctor Manuel , Serrano Fiz Santiago , Burgos Lázaro Raúl , García-Pavía Pablo , Mitjavila Casanovas Mercedes , Forteza Gil Alberto
Published: January 2021

OBJECTIVES

Our goal was to define characteristic patterns of 18F-fluorodeoxyglucose in non-infected patients with ascending aortic prosthetic grafts during the first year after surgery.

METHODS

18F-fluorodeoxyglucose positron emission tomography (PET)/computed tomography (CT) was performed at 3, 6 and 12 months postoperatively in 26 uninfected patients. Clinical, analytical and microbiological (blood culture) assessments were performed to confirm the absence of infection. FDG uptake intensity [measured through maximum standardized uptake values (SUVmax) and the target-to-background ratio] and distribution patterns were obtained. Models of generalized estimating equations were used to assess the evolution of the SUVmax over time. The results were compared to those in our endocarditis-over-ascending-aortic-graft series database. The receiver operating characteristic curves of the control group and the 12-month group were assessed.

RESULTS

All patients showed increased uptake in all areas. The uptake pattern was heterogeneous in 47.4%, 43.5% and 42.3% at 3, 6 and 12 months. The means and standard deviations of the SUVmax in the graft were 4.80 (±0.99), 4.28 (±0.88) and 4.14 (±0.87) at 3, 6 and 12 months after surgery. A comparison of all values obtained in the 6th and 12th months compared to those from the 3rd month revealed a slow decrease that may persist after the first year. The cut-off value of SUVmax of 4.24 had an overall sensitivity of 84.6% and specificity of 57.7% for patients seen at 12 months.

CONCLUSIONS

Non-infected ascending aortic grafts showed no predominant uptake pattern; they also showed increased 18F-fluorodeoxyglucose activity that could persist beyond the first year. Caution is therefore recommended when interpreting PET/CT images obtained during the first year after surgery.
Exercise intensity assessment and prescription in cardiovascular rehabilitation and beyond: why and how: a position statement from the Secondary Prevention and Rehabilitation Section of the European Association of Preventive Cardiology
Authors: Hansen Dominique , Abreu Ana , Ambrosetti Marco , Cornelissen Veronique , Gevaert Andreas , Kemps Hareld , Laukkanen Jari A , Pedretti Roberto , Simonenko Maria , Wilhelm Matthias , Davos Constantinos H , Doehner Wolfram , Iliou Marie-Christine , Kränkel Nicolle , Völler Heinz , Piepoli Massimo
Published: January 2021

A proper determination of the exercise intensity is important for the rehabilitation of patients with cardiovascular disease (CVD) since it affects the effectiveness and medical safety of exercise training. In 2013, the European Association of Preventive Cardiology (EAPC), together with the American Association of Cardiovascular and Pulmonary Rehabilitation and the Canadian Association of Cardiac Rehabilitation, published a position statement on aerobic exercise intensity assessment and prescription in cardiovascular rehabilitation (CR). Since this publication, many subsequent papers were published concerning the determination of the exercise intensity in CR, in which some controversies were revealed and some of the commonly applied concepts were further refined. Moreover, how to determine the exercise intensity during resistance training was not covered in this position paper. In light of these new findings, an update on how to determine the exercise intensity for patients with CVD is mandatory, both for aerobic and resistance exercises. In this EAPC position paper, it will be explained in detail which objective and subjective methods for CR exercise intensity determination exist for aerobic and resistance training, together with their (dis)advantages and practical applications.
Dechloromonasand close relatives prevail during hydrogenotrophic denitrification in stimulated microcosms with oxic aquifer material
Authors: Duffner Clara , Holzapfel Sebastian , Wunderlich Anja , Einsiedl Florian , Schloter Michael , Schulz Stefanie
Published: January 2021

Globally occurring nitrate pollution in groundwater is harming the environment and human health. In situ hydrogen addition to stimulate denitrification has been proposed as a remediation strategy. However, observed nitrite accumulation and incomplete denitrification are severe drawbacks that possibly stem from the specific microbial community composition. We set up a microcosm experiment comprising sediment and groundwater from a nitrate polluted oxic oligotrophic aquifer. After the microcosms were sparged with hydrogen gas, samples were taken regularly within 122 h for nitrate and nitrite measurements, community composition analysis via 16S rRNA gene amplicon sequencing and gene and transcript quantification via qPCR of reductase genes essential for complete denitrification. The highest nitrate reduction rates and greatest increase in bacterial abundance coincided with a 15.3-fold increase in relative abundance of Rhodocyclaceae, specifically six ASVs that are closely related to the genus Dechloromonas. The denitrification reductase genes napA, nirS and clade I nosZ also increased significantly over the observation period. We conclude that taxa of the genus Dechloromonas are the prevailing hydrogenotrophic denitrifiers in this nitrate polluted aquifer and the ability of hydrogenotrophic denitrification under the given conditions is species-specific.
Evaluating accessibility, usability and interoperability of genome-scale metabolic models for diverse yeasts species
Authors: Domenzain Iván , Li Feiran , Kerkhoven Eduard J , Siewers Verena
Published: January 2021

Metabolic network reconstructions have become an important tool for probing cellular metabolism in the field of systems biology. They are used as tools for quantitative prediction but also as scaffolds for further knowledge contextualization. The yeast Saccharomyces cerevisiae was one of the first organisms for which a genome-scale metabolic model (GEM) was reconstructed, in 2003, and since then 45 metabolic models have been developed for a wide variety of relevant yeasts species. A systematic evaluation of these models revealed that—despite this long modeling history—the sequential process of tracing model files, setting them up for basic simulation purposes and comparing them across species and even different versions, is still not a generalizable task. These findings call the yeast modeling community to comply to standard practices on model development and sharing in order to make GEMs accessible and useful for a wider public.
A long-term conserved satellite DNA that remains unexpanded in several genomes of Characiformes fish is actively transcribed
Authors: dos Santos Rodrigo Zeni , Calegari Rodrigo Milan , Silva Duílio Mazzoni Zerbinato de Andrade , Ruiz-Ruano Francisco J , Melo Silvana , Oliveira Claudio , Foresti Fausto , Uliano-Silva Marcela , Foresti Fábio Porto , Utsunomia Ricardo
Published: January 2021

Eukaryotic genomes contain large amounts of repetitive DNA sequences, such as tandemly repeated satellite DNAs (satDNAs). These sequences are highly dynamic and tend to be genus- or species-specific due to their particular evolutionary pathways, although there are few unusual cases of conserved satDNAs over long periods of time. Here, we used multiple approaches to reveal that a satDNA named CharSat01-52 originated in the last common ancestor of Characoidei fish, a superfamily within the Characiformes order, approximately 140–78 million years ago, while its nucleotide composition has remained considerably conserved in several taxa. We show that 14 distantly related species within Characoidei share the presence of this satellite DNA, which is highly amplified and clustered in subtelomeric regions in a single species (Characidium gomesi), while remained organized as small clusters in all the other species. Defying predictions of the molecular drive of satellite evolution, CharSat01-52 shows similar values of intra- and interspecific divergence. Although we did not provide evidence for a specific functional role of CharSat01-52, its transcriptional activity was demonstrated in different species. In addition, we identified short tandem arrays of CharSat01-52 embedded within SMRT long reads of Astyanax paranae (536 bp to 3.1 kb) and A. mexicanus (501 bp to 3.9 kb). Such arrays consisted of head-to-tail repeats and could be found interspersed with other sequences, inverted sequences or neighbored by other satellites. Our results provide a detailed characterization of an old and conserved satDNA, challenging general predictions of satellite DNA evolution.
CHROMOSOMAL LOCATION OF PLEIOTROPIC NEGATIVE SPORULATION MUTATIONS IN BACILLUS SUBTILIS
Authors: Hoch James A , Mathews Judith L
Published: January 2021

Genetic analysis by PBS-1 transduction and transformation of a large group of pleiotropic negative sporulation mutants has shown that mutations of this phenotype may be located in five genetically distinct regions. The first group of mutant sites, spoA mutations, is located in the terminal region of the chromosome and linked to the lys-I marker by PBS-1 transduction. The second group, spoB mutations, is located between phe-I and the attachment site for the lysogenic bacteriophage Φ 105. Fine structure analysis of the mutant sites within the spoB locus has been accomplished. A third location for mutants of this phenotype, spoE mutants, was found between the metC3 and ura-I markers. Two mutants were found at this site and both were capable of sporulation, in contrast to the rest of the pleiotropic sporulation mutants. A fourth chromosomal site, spoH mutations, was found near the ribosomal and RNA polymerase loci. A large group of mutant sites, spoF mutations, was found to be linked to each other by recombination index analysis in transformation but unlinked to any of the known auxotrophic mutations comprising the chromosomal map. All mutants analyzed showing a pleiotropic negative phenotype were found to map within one of these five regions. Interspecific transformation with Bacillus anyloliquefaciens as donor has shown that all of the pleiotropic negative sporulation mutations are conserved relative to a selected group of auxotrophic markers. The degree of conservation in decreasing order is: spoH > spoF = spoB > spoA
NONSENSE MOTILITY MUTANTS IN SALMONELLA TYPHIMURIUM
Authors: Vary Patricia S , Stocker Bruce A D
Published: January 2021

Of 313 motility-deficient mutants isolated from an LT2 his(amber) strain fixed in phase 1 by gene vh2-, 25 regained motility when amber or ochre suppressors were introduced, in F' factors or by transduction. The fla mutants (23 amber, 1 ochre) fell in complementation groups A, B, C, F, K, a new group, M, and at least one further new group; the hypothesis of a fla gene which specifies only an RNA structural component of a flagellum-synthesizing basal apparatus is disproven for the corresponding genes. Hfr and transductional crosses confirmed gene assignments from complementation and indicated that flaM and another new fla locus map near H1. A small minority of motile bacteria were detectable in many of the amber fla mutants. In groups A and F some pairs of amber fla mutants complemented each other, and perhaps each of these groups corresponds to more than one structural gene. The suppressed derivatives of a mutant with an amber mutation in H1 made flagella morphologically and serologically indistinguishable from wild-type flagella. A slowspreading but flagellate mutant showed mainly non-translational motility in broth, and in a viscocs medium the bacteria reversed very frequently; its amber mutation, probably near H1, is inferred to cause a defect in chemotaxis, so that the bacteria give the avoidance reaction continuously.
DIRECTIONAL CYTOTOXIC REACTIONS BETWEEN INCOMPATIBLE PLASMODIA OF DIDYMIUM IRIDIS
Authors: Clark Jim , Collins O'Neil Ray
Published: January 2021

Incompatibility reactions of somatic cells in the myxomycete Didymium iridis are controlled by several loci displaying simple dominance. Phenotypically dissimilar plasmodia generally undergo a temporary fusion which is quickly terminated by a cytotoxic reaction, whereas phenotypically similar ones undergo fusion which is not followed by such reactions. The size of the killed areas varies from microscopic up to a few square centimeters and is directly correlated with the amount of protoplasmic mixing which occurs. The amount of mixing itself is controlled by the incompatibility loci through regulation of the speed of killing. Each locus allows a characteristic amount of mixing and when two or more loci act together the amount is reduced by a subtractive effect. This results in a smaller killed area because of the more rapid cytotoxic reaction. Such a reaction is also unidirectional for each locus, with killing taking place in the recessive phenotype. Reversion of some heterokaryons to a homokaryotic state within 24 hours is considered evidence for the existence of unidentified weak incompatibility loci which act very slowly.
CYTOPLASMIC INHERITANCE OF CHLORAMPHENICOL RESISTANCE IN TETRAHYMENA
Authors: Roberts Charles T , Orias Eduardo
Published: January 2021

Chloramphenicol-resistant mutants of Tetrahymena pyriform's were obtained after mutagenesis with nitrosoguanidine at an estimated frequency of 10-3 mutants per mutagenized cell. The mutants are still partially sensitive to chloramphenicol and have a lowered growth rate, compared to the wild type strain, in rich medium without chloramphenicol. The genetic analysis described here indicates that chloramphenicol resistance is inherited as a cytoplasmic determinant that is not exchanged during conjugation. This represents the first simple cytoplasmic genetic determinant described in this species. A number of arguments favor a mitochondrial localization for this genetic determinant. In addition to the possible utility of such mutants for studies of mitochondrial structure and function in Tetrahymena, analogous mutations might serve as cytoplasmic "tags" in other ciliate species where the results of selfing need to be distinguished from those of outcrossing.
MUTABLE R-NAVAJO ALLELES OF CYCLIC ORIGIN IN MAIZE
Authors: Brink R Alexander , Williams Elizabeth
Published: January 2021

The generation in cyclic fashion of 26 mutable R-Navajo (mRnj) alleles in maize involved transposition of a non-specific repressor of gene action, Modulator (Mp), first away from, and then back to, the R locus represented by the R-Navajo (Rnj) all ele on chromosome 10. The mPnj alleles reconstituted in this way vaned widely, and continuously, in mutability to Rnj-that is, in transposition of Mp away from the R locus, thus derepressing the Rnj gene. They were alike, or nearly so, however, in activating Ds chromosome breakage and in increasing the stability of variegated pericarp, another unstable compound allele comprising Mp conjoined with Prr on chromosomal 1. These latter two phenomena are based primarily on loci elsewhere in the genome. It is postulated that the 26 reconstituted mRnj alleles carry a common Mp which, however, is intercalated at a different site within each allele. Nucleotide sequence in the regions adjacent to Mp is assumed to determine the frequency with which a form of micro-nondisjunction occurs whereby Mp is released from a donor site. Transposition to a new site is interpreted in terms of a chromosome model that gives effect to nicking, or single strand breaks, occurring throughout the genome as a prerequisite to unwinding, strand separation, and replication, of the DNA double helix.
INHERITANCE OF PLASMA CHOLESTEROL LEVELS IN MICE
Authors: Weibust Robert S
Published: January 2021

Mean plasma cholesterol levels were determined at two ages in mice from eight unrelated inbred strains (BALB/cJ, BDP/J, CBA/J, C57BL/6J, LP/J, RF/J, SJL/J, and 129/J). Significant strain, sex, and age differences were observed. Estimates of the degree of genetic determination of the trait obtained from an analysis of the strain data averaged 58 ± 4% for the males and 54 ± 8% for the females.—Selection for high and low plasma cholesterol levels produced two significantly different and distinct lines. Selection was initiated in a genetically heterogeneous population derived from an eight-way cross of the inbred strains listed above. After five generations of selection the divergence of the high and low lines amounted to 4 phenotypic standard deviations of the foundation population. Realized heritability estimated from the regression of divergence on the combined cumulative selection differential was 51 ± 5% for the males and 50 ± 3% for the females. The results indicate that genetic factors are important in controlling plasma cholesterol levels in the mouse and that the majority of these factors act additively.
THE VARIANCE OF THE NUMBER OF LOCI HAVING A GIVEN GENE FREQUENCY
Authors: Maruyama Takeo
Published: January 2021

Considering a random mating population of finite size, the variance of the number of loci having a given gene frequency was derived under the assumption of a steady flux of mutations. The variance of average heterozygosity among populations was also derived under the same assumption. It was shown that these variances are proportional to the population size if the mutants are selectively neutral, and they are inversely proportional to the selection coefficient if the mutants are selectively advantageous and additive in their fitness.
MITOCHONDRIAL GENETIC ANALYSIS BY ZYGOTE CELL LINEAGES IN SACCHAROMYCES CEREVISIAE
Authors: Wilkie D , Thomas D Y
Published: January 2021

Yeast strains were constructed carrying multiple mitochondrial markers conferring resistance to the inhibitors erythromycin, chloramphenicol, paromomycin and oligomycin. A pedigree analysis of two crosses was made by micromanipulating buds from zygotes. The first few daughter buds isolated from the zygotes sometimes gave rise to diploid clones which had a mixture of mitochondrial types. All possible classes of mitochondrial parental and recombinant types were found although they never appeared all together as the progeny from a single zygote. It was inferred that multiple recombination events took place in zygotes and in some of the buds derived from them. After removal of the first four or so daughter buds, subsequent buds from the zygote carried one mitochondrial type only. In cross I in which three markers were analyzed this was most frequently one of the parental types. In cross II (involving four mitochondrial markers) the later buds from the zygotes were frequently of recombinant mitochondrial type.
THE MECHANISM OF SOMATIC ASSOCIATION IN COMMON WHEAT, TRITICUM AESTIVUM L. IV. FURTHER EVIDENCE FOR MODIFICATION OF SPINDLE TUBULIN THROUGH THE SOMATIC-ASSOCIATION GENES AS MEASURED BY VINBLASTINE BINDING
Authors: Avivi Lydia , Feldman Moshe
Published: January 2021

Treatment with the antitubulin vinblastine was found to disrupt the spindle system in dividing root-tip cells of common wheat, Triticum aestivum L. Genotypes lacking the somatic association suppressor gene on 5BL, or containing the somatic-association promoter on 5BS, were found to be more sensitive to the treatment. In genetic lines carrying the somatic association suppressor, sensitivity to vinblastine was lower and there was a direct correlation between dosage of the suppressor gene (0, 2, and 4) and the decrease in spindle disruption on exposure to various concentrations of vinblastine. It is concluded that the somatic association genes affect binding ability of spindle tubulin to vinblastine. Since the same genes affect binding of colchicine to tubulin and since the two alkaloids attach to different sites it is assumed that the somatic association suppressor gene has a broad effect on the tubulin molecules which is not confined to a single site. The relevance of genetic control of antitubulin binding to somatic association is discussed.
NONDISJUNCTION: LOCALIZATION OF THE CONTROLLING SITE IN THE MAIZE B CHROMOSOME
Authors: Ward Edward J
Published: January 2021

Nondisjunction of the B chromosome in maize has been considered to be controlled by heterochromatin in its long arm. Experiments reported here indicate that the control site actually lies in a short, relatively euchromatic segment distal to the major heterochromatin of the long arm.
DIFFERENTIATION OF DROSOPHILA CELLS LACKING RIBOSOMAL DNA, IN VITRO
Authors: Donady J James , Seecof R L , Fox M A
Published: January 2021

Drosophila melanogaster embryos that lacked ribosomal DNA were obtained from appropriate crosses. Cells were taken from such embryos before overt differentiation took place and were cultured in vitro. These cells differentiated into neurons and myocytes with the same success as did wild-type controls. Therefore, ribosomal RNA synthesis is not necessary for the differentiation of neurons and myocytes in vitro.
IS THE NOTCH LOCUS OF DROSOPHILA MELANOGASTER A TANDEM REPEAT? CORRELATION OF THE GENETIC MAP AND COMPLEMENTATION PATTERN OF SELECTED MUTATIONS
Authors: Foster Geoffrey G
Published: January 2021

Correlation of the complementation relationships between the Notch locus alleles fag, fano, Ax59d and nd, with their genetic map order, suggests a tandem repetition within the locus of functionally related sites. This observation is discussed in relation to two hypotheses: (1) that the Notch locus contains a tandem repeat of genetic material; and (2) that the tertiary structure of the Notch locus product has a spiral configuration.
A MEIOTIC MUTANT AFFECTING RECOMBINATION IN FEMALE DROSOPHILA MELANOGASTER
Authors: Parry Dilys M
Published: January 2021

mei-S282 is a female meiotic mutant isolated from a natural population of Drosophila melanogaster. It is a recessive mutation located at approximately map position 5 on the third chromosome which has two major effects. It causes a nonuniform decrease in recombination which is most drastic in distal chromosome regions and nondisjunction of all chromosome pairs is elevated at the first meiotic division. Nondisjunctional events are positively correlated; furthermore, nondisjoining chromosomes, themselves nonrecombinant, are preferentially recovered from cells in which nonhomologs are preferentially recovered from cells in which nonhomologs are also non-recombinant.—It is concluded that mei-S282 is a defect which occurs early in meiosis I prior to the time of exchange. In the mutant, the frequency of no-exchange tetrads for each of the major chromosomes is increased—and in cells which contain two or more no-exchange tetrads, an interaction between these chromosomes leads to correlated nondisjunction. mei-S282  + then, is an exchange precondition necessary for the normal frequency and distribution of exchanges.
SENSITIVITY OF MEIOTIC YEAST CELLS TO ULTRAVIOLET LIGHT
Authors: Simchen G , Salts Y , Piñon R
Published: January 2021

Sporulating cells of Szccharomyces cereuisiae show an increasing sensitivity to ultraviolet irradiation. Maximum sensitivity is reached at a time comparable to meiotic prophase. Sensitivity is expressed as reduced sporulation after the irradiation. The uv effect can be efficiently reversed by photoreactivating light. Viability is also morc severely affected during premeiotic DNA synthesis and during meiosis than in earlier stages in sporulation. Cells left in sporulation medium after the irradiation show a reduced viability compared with the cells plated immediately after the irradiation. Non-sporulating diploids do not acquire sensitivity when exposed to sporulation medium, hence the sensitivity is related to the sporulation process. That meiosis itself is affected, rather than spore formation alone, is evident from experiments in which the uv irradiation interferes with the uncovering of a recessive marker and with commitment to meiosis. It is proposed that during meiotic prophase, the DNA repair system is different from that found in vegetative cells.
USE OF GENOMIC EXCLUSION TO ISOLATE HEAT-SENSITIVE MUTANTS IN TETRAHYMENA
Authors: Orias Eduardo , Flacks Miriam
Published: January 2021

We have used the abnormal form of conjugation known as "genomic exclusion" to isolate a collection of heat-sensitive mutants of Tetrahymena pyriformis, syngen 1. Growth at room temperature in bacterized medium and no growth at 40°C in the same medium was the criterion used for the isolation. The mutant strains were tested for growth in pure (axenic) culture in proteose peptone medium; of the 31 strains which grew normally at room temperature and not at 40°C in that medium, 21 also failed to grow at 37°C. Preliminary results of complementation tests suggest that most, if not all, the mutations are recessive and that a variety of genes was affected. A detailed genetic analysis was performed on one mutant (H9). The results are all consistent with the idea that the heat-sensitive phenotype of this mutant is determined by a single recessive mutation, designated ts-2. Heterozygotes ts-2/+ yield heat-sensitive segregants during vegetative growth; we interpret this finding as another example of allelic exclusion, a phenomenon universally encountered among heterozygotes in syngen 1 of T. pyriformis. Our results are discussed in the context of some questions of current interest in Tetrahymena genetics.
ESTERASE VARIATIONS BETWEEN THE 14 SYNGENS OF PARAMECIUM AURELIA UNDER AXENIC GROWTH
Authors: Allen S L , Farrow S W , Golembiewski P A
Published: January 2021

Under axenic growth all 14 syngens of Paramecium aurelia have 4 types of esterases. The three major types (A, B and cathodal C) vary independently in electrophoretic mobility among the syngens. Using these three esterases, stocks can be keyed to a syngen, except for the groupings 1-3-5 and 7-13. Using 5 other enzymes only syngens 1 and 5 cannot be distinguished. Most syngens differ from each other in 6 out of the 8 enzymes. An axenically-grown stock of Paramecium multimicronucleatum collected in Costa Rica has the same types of esterases as P. aurelia. Two of the types (A and C) are similar in mobility to those found in syngens 7 and 13, but its B esterase differs in mobility from all the known syngens of P. aurelia.