bluuebunny/crossref_metadata_2025 huggingface dataset:
Insights about the epidemiology of Salmonella Typhimurium isolates from different sources in Brazil using comparative genomics
Authors: Seribelli Amanda Ap. , da Silva Patrick , da Cruz Marcelo Ferreira , de Almeida Fernanda , Frazão Miliane R. , Medeiros Marta I. C. , Rodrigues Dália dos P. , Kich Jalusa D. , de Jesus Benevides Leandro , Soares Siomar de C. , Allard Marc W. , Falcão Juliana Pfrimer.
Published: April 2021

Background

Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) is an important zoonotic agent worldwide. The aim of this work was to compare genetically 117 S. Typhimurium isolated from different sources over 30 years in Brazil using different genomics strategies.

Results

The majority of the 117 S. Typhimurium strains studied were grouped into a single cluster (≅ 90%) by the core genome multilocus sequence typing and (≅ 77%) by single copy marker genes. The phylogenetic analysis based on single nucleotide polymorphism (SNP) grouped most strains from humans into a single cluster (≅ 93%), while the strains isolated from food and swine were alocated into three clusters. The different orthologous protein clusters found for some S. Typhimurium isolated from humans and food are involved in metabolic and regulatory processes. For 26 isolates from swine the sequence types (ST) 19 and ST1921 were the most prevalent ones, and the ST14, ST64, ST516 and ST639 were also detected. Previous results typed the 91 S. Typhimurium isolates from humans and foods as ST19, ST313, ST1921, ST3343 and ST1649. The main prophages detected were: Gifsy-2 in 79 (67.5%) and Gifsy-1 in 63 (54%) strains. All of the S. Typhimurium isolates contained the acrA, acrB, macA, macB, mdtK, emrA, emrB, emrR and tolC efflux pump genes.

Conclusions

The phylogenetic trees grouped the majority of the S. Typhimurium isolates from humans into a single cluster suggesting that there is one prevalent subtype in Brazil. Regarding strains isolated from food and swine, the SNPs’ results suggested the circulation of more than one subtype over 30 years in this country. The orthologous protein clusters analysis revealed unique genes in the strains studied mainly related to bacterial metabolism. S. Typhimurium strains from swine showed greater diversity of STs and prophages in comparison to strains isolated from humans and foods. The pathogenic potential of S. Typhimurium strains was corroborated by the presence of exclusive prophages of this serovar involved in its virulence. The high number of resistance genes related to efflux pumps is worrying and may lead to therapeutic failures when clinical treatment is needed.
Performance measurement for new mobile data services during generation upgrading period: a case of China’s telecom industry
Authors: Du Yu , Zhang Xiao H. , Li Zheng R. , Guo Yi J.
Published: April 2021

For the global telecom operators, mobile data services have gradually taken the part of traditional voice services to become the main revenue growth point. However, during the upgrading period of new generation networks (such as 5G), new mobile data services are still at the stage of exploration; the network capabilities and the application scenarios are unmatured. In this phase, it is incomplete and misleading to simply measure the performance of new services from one dimension, such as data traffic or revenue, and the measurement should be dynamically changed according to the development of the new services. Therefore, telecom operators want to improve the existing performance measurement from the aspect of integrity and dynamics. In this paper, we propose mobile-data-service development index (MDDI) and build a quantitative model to dynamic measure the overall performance of mobile data services. To approach a fuller understanding, we creatively bring investment indicators and networks reliability indicators into performance indicators system and discuss the relationships among subindices and the selection of outcome criteria in MDDI. In the part of empirical research, we use the model to analyze the dynamic characteristics of a new mobile data service in China and summarize the development strategies of every stage. The findings can also give guidelines for new services of 5G and other new generation networks in the future.
On oscillation of second-order noncanonical neutral differential equations
Authors: Muhib Ali
Published: April 2021

In the present work, we study the second-order neutral differential equation and formulate new oscillation criteria for this equation. Our conditions differ from the earlier ones. Also, our results are expansions and generalizations of some previous results. Examples to illustrate the main results are included.
Identification of a prognostic long noncoding RNA signature in lung squamous cell carcinoma: a population-based study with a mean follow-up of 3.5 years
Authors: Zheng Rongjiong , Zheng Mengdi , Wang Mingming , Lu Feijie , Hu Meiling
Published: April 2021

Background

Lung squamous cell carcinoma (LSCC) is a form of cancer that is associated with high rates of relapse, poor responsiveness to therapy, and a relatively poor prognosis. The relationship between long non-coding RNA (lncRNA) expression and LSCC patient prognosis remains to be established.

Methods

In the present study, we discovered that lncRNAs were differentially expressed in LSCC tumor tissues relative to normal control tissues, and we explored the prognostic relevance of these lncRNA expression patterns using data from the Cancer Genome Atlas (TCGA).

Results

These multidimensional data were analyzed in order to identify lncRNA signatures that were associated with LSCC patient survival outcomes. Kaplan-Meier survival curves revealed prognostic capabilities for three of these lncRNAs (LINC02555, APCDD1L-DT and OTX2-AS1). A Cox regression analysis revealed this three-lncRNA signature to be significantly associated with patient survival. Further GO and KEGG analyses revealed that the predicted target genes of these three lncRNAs were also potentially involved in cancer-associated pathways.

Conclusions

Together these results thus indicate that this novel three-lncRNA signature can be used to predict LSCC patient prognosis.
Role of preoperative computed tomography angiographic anatomical considerations and their intraoperative interpretations in prediction of outcome in microsurgical clipping of ruptured anterior communicating aneurysm
Authors: Alawamry Ahmed Mohamed Ehsan , Taha Mahmoud Mostafa , Abdelbary Tarek Hassan , Bessar Ahmed Awad , Farid Mostafa
Published: April 2021

Background

Anatomy of anterior communicating vascular complex is variable and sometimes causes troublesome situations during microsurgical clipping of ruptured anterior communicating (Acom) aneurysms. Preoperative understanding of anatomy, expecting the presence of normal variations, knowing the exact aneurysm morphometrics and understanding flow dynamic patterns, help to reach an appropriate surgical outcome.

Methods

We analyzed the preoperative angiographic anatomical findings in computed tomography angiography and compared them to the intraoperative microscopic anatomical finding in 52 patients who underwent microsurgical clipping of ruptured Acom aneurysms, to reach angiographic prognostic factors in ruptured Acom aneurysm surgery.

Results

There is statistically significant relation between intraoperative anatomical factors and preoperative CTA findings (closed A2 aneurysm angle, neck extending to A2, anatomical variation, hypoplastic A1, and posterior projection).

Conclusion

CTA is a reliable method to predict the intraoperative anatomy in Acom aneurysm clipping. Poor outcome was more common among cases with posterior projection, closed A2-aneurysm angle, aneurysm neck extension to A2, and hypoplastic A1.
Insights into genomic evolution from the chromosomal and mitochondrial genomes of Ustilaginoidea virens
Authors: Zhang Kang , Zhao Zaixu , Zhang Ziding , Li Yuejiao , Li Shaojie , Yao Nan , Hsiang Tom , Sun Wenxian
Published: April 2021

Ustilaginoidea virens, the causal agent of rice false smut, is an economically important filamentous fungal pathogen. A high-quality reference genome of U. virens promotes understanding of molecular mechanisms underlying its virulence and pathogenicity. Here, we report the first chromosome-level assembly of U. virens genome consisting of seven chromosomes ranging from 2.4 to 7.5 Mb. The assembly has dramatic improvements over previous assemblies, including considerably longer contigs, higher proportion of repetitive elements and more functionally annotated genes. Phylogenetic analyses revealed an extremely low intraspecific sequence divergence in U. virens. By contrast, intraspecific genome comparisons uncovered dynamic genomic alterations including massive structural variations and widespread lineage-specific regions (LSRs) among U. virens strains, which were mainly generated by recent burst of retrotransposons. Genomic plasticity created by structural variations and LSRs might drive rapid evolution of U. virens. High-quality mitochondrial genomes of eight U. virens strains exhibit size variations from 94 to 102 kb. Consistently, U. virens contains conserved lengths of exons and highly dynamic mobile introns, which contribute to intraspecific size variations due to gain/loss of homing endonuclease genes. This study highlights unique characteristics in nuclear and mitochondrial genomic divergence and provides new insights into genomic and mitochondrial evolution of U. virens.
Comparative evaluation of semi-quantitative CT-severity scoring versus serum lactate dehydrogenase as prognostic biomarkers for disease severity and clinical outcome of COVID-19 patients
Authors: Magdy Ahmed M. , Saad Mohammad A. , El Khateeb Ahmed F. , Ahmed Mona I. , Gamal El-Din Dina H.
Published: April 2021

Background

Coronavirus disease 2019 pandemic causes significant strain on healthcare infrastructure and medical resources. So, it becomes crucial to identify reliable predictor biomarkers for COVID-19 disease severity and short term mortality. Many biomarkers are currently investigated for their prognostic role in COVID-19 patients. Our study is retrospective and aims to evaluate role of semi-quantitative CT-severity scoring versus LDH as prognostic biomarkers for COVID-19 disease severity and short-term clinical outcome.

Results

Two hundred sixty-six patients between April 2020 and November 2020 with positive RT-PCR results underwent non-enhanced CT scan chest in our hospital and were retrospectively evaluated for CT severity scoring and serum LDH level measurement. Data were correlated with clinical disease severity. CT severity score and LDH were significantly higher in severe and critical cases compared to mild cases (P value < 0.001). High predictive significance of CT severity score for COVID-19 disease course noted, with cut-off value ≥ 13 highly predictive of severe disease (96.96% accuracy); cut-off value ≥ 16 highly predictive of critical disease (94.21% accuracy); and cut-off value ≥ 19 highly predictive of short-term mortality (92.56% accuracy). CT severity score has higher sensitivity, specificity, positive, and negative predictive values as well as overall accuracy compared to LDH level in predicting severe, critical cases, and short-term mortality.

Conclusion

Semi-quantitative CT severity scoring has high predictive significance for COVID-19 disease severity and short-term mortality with higher sensitivity, specificity, and overall accuracy compared to LDH. Our study strongly supports the use of CT severity scoring as a powerful prognostic biomarker for COVID-19 disease severity and short-term clinical outcome to allow triage of need for hospital admission, earlier medical interference, and to effectively prioritize medical resources for cases with high mortality risk for better decision making and clinical outcome.
Trends in International Cancer Research Investment 2006-2018
Authors: Abudu Rachel , Bouche Gauthier , Bourougaa Karima , Davies Lynne , Duncan Kalina , Estaquio Carla , Font Anna Diaz , Hurlbert Marc S. , Jackson Paul , Kroeskop-Bossenbroek Linda , Lewis Ian , Mitrou Giota , Mutabbir Abdul , Pettigrew Christopher A. , Turner Lynn , Weerman Annemarie , Wojtanik Kari
Published: April 2021

The International Cancer Research Partnership (ICRP) is an active network of cancer research funding organizations, sharing information about funded research projects in a common database. Data are publicly available to enable the cancer research community to find potential collaborators and avoid duplication. This study presents an aggregated analysis of projects funded by 120 partner organizations and institutes in 2006-2018, to highlight trends in cancer research funding. Overall, the partners’ funding for cancer research increased from $5.562 billion (bn) US dollars (USD) in 2006 to $8.511bn USD in 2018, an above-inflation increase in funding. Analysis by the main research focus of projects using Common Scientific Outline categories showed that Treatment was the largest investment category in 2018, followed by Early Detection, Diagnosis, and Prognosis; Cancer Biology; Etiology; Control, Survivorship, and Outcomes; and Prevention. Over the 13 years covered by this analysis, research funding into Treatment and Early Detection, Diagnosis, and Prognosis had increased in terms of absolute investment and as a proportion of the portfolio. Research funding in Cancer Biology and Etiology declined as a percentage of the portfolio, and funding for Prevention and Control, Survivorship and Outcomes remained static. In terms of cancer site–specific research, funding for breast cancer and colorectal cancer had increased in absolute terms but declined as a percentage of the portfolio. By contrast, investment for brain cancer, lung cancer, leukemia, melanoma, and pancreatic cancer increased both in absolute terms and as a percentage of the portfolio.
Cell-Free DNA Detection of Tumor Mutations in Heterogeneous, Localized Prostate Cancer Via Targeted, Multiregion Sequencing
Authors: Chen Emmalyn , Cario Clinton L. , Leong Lancelote , Lopez Karen , Márquez César P. , Li Patricia S. , Oropeza Erica , Tenggara Imelda , Cowan Janet , Simko Jeffry P. , Kageyama Robin , Wells Daniel K. , Chan June M. , Friedlander Terence , Aggarwal Rahul , Paris Pamela L. , Feng Felix , Carroll Peter R. , Witte John S.
Published: April 2021

PURPOSE

Cell-free DNA (cfDNA) may allow for minimally invasive identification of biologically relevant genomic alterations and genetically distinct tumor subclones. Although existing biomarkers may detect localized prostate cancer, additional strategies interrogating genomic heterogeneity are necessary for identifying and monitoring aggressive disease. In this study, we aimed to evaluate whether circulating tumor DNA can detect genomic alterations present in multiple regions of localized prostate tumor tissue.

METHODS

Low-pass whole-genome and targeted sequencing with a machine-learning guided 2.5-Mb targeted panel were used to identify single nucleotide variants, small insertions and deletions (indels), and copy-number alterations in cfDNA. The majority of this study focuses on the subset of 21 patients with localized disease, although 45 total individuals were evaluated, including 15 healthy controls and nine men with metastatic castration-resistant prostate cancer. Plasma cfDNA was barcoded with duplex unique molecular identifiers. For localized cases, matched tumor tissue was collected from multiple regions (one to nine samples per patient) for comparison.

RESULTS

Somatic tumor variants present in heterogeneous tumor foci from patients with localized disease were detected in cfDNA, and cfDNA mutational burden was found to track with disease severity. Somatic tissue alterations were identified in cfDNA, including nonsynonymous variants in FOXA1, PTEN, MED12, and ATM. Detection of these overlapping variants was associated with seminal vesicle invasion ( P = .019) and with the number of variants initially found in the matched tumor tissue samples ( P = .0005).

CONCLUSION

Our findings demonstrate the potential of targeted cfDNA sequencing to detect somatic tissue alterations in heterogeneous, localized prostate cancer, especially in a setting where matched tumor tissue may be unavailable (ie, active surveillance or treatment monitoring).
Strategies to Develop Potent Oncolytic Viruses and Enhance Their Therapeutic Efficacy
Authors: Moaven Omeed , Mangieri Christopher W. , Stauffer John A. , Anastasiadis Panos Z. , Borad Mitesh J.
Published: April 2021

Despite advancements in cancer therapy that have occurred over the past several decades, successful treatment of advanced malignancies remains elusive. Substantial resources and significant efforts have been directed toward the development of novel therapeutic modalities to improve patient outcomes. Oncolytic viruses (OVs) are emerging tools with unique characteristics that have attracted great interest in developing effective anticancer treatment. The original attraction was directed toward selective replication and cell-specific toxicity, two unique features that are either inherent to the virus or could be conferred by genetic engineering. However, recent advancements in the knowledge and understanding of OVs are shifting the therapeutic paradigm toward a greater focus on their immunomodulatory role. Nonetheless, there are still significant obstacles that remain to be overcome to enhance the efficiency of OVs as effective therapeutic modalities and potentially establish them as part of standard treatment regimens. In this review, we discuss advances in the design of OVs, strategies to enhance their therapeutic efficacy, functional translation into the clinical settings, and various obstacles that are still encountered in the efforts to establish them as effective anticancer treatments.
Vasopressors in Trauma: A Never Event?
Authors: Richards Justin E. , Harris Tim , Dünser Martin W. , Bouzat Pierre , Gauss Tobias
Published: April 2021

Vasopressor use in severely injured trauma patients is discouraged due to concerns that vasoconstriction will worsen organ perfusion and result in increased mortality and organ failure in hypotensive trauma patients. Hypotensive resuscitation is advocated based on limited data that lower systolic blood pressure and mean arterial pressure will result in improved mortality. It is classically taught that hypotension and hypovolemia in trauma are associated with peripheral vasoconstriction. However, the pathophysiology of traumatic shock is complex and involves multiple neurohormonal interactions that are ultimately manifested by an initial sympathoexcitatory phase that attempts to compensate for acute blood loss and is characterized by vasoconstriction, tachycardia, and preserved mean arterial blood pressure. The subsequent hypotension observed in hemorrhagic shock reflects a sympathoinhibitory vasodilation phase. The objectives of hemodynamic resuscitation in hypotensive trauma patients are restoring adequate intravascular volume with a balanced ratio of blood products, correcting pathologic coagulopathy, and maintaining organ perfusion. Persistent hypotension and hypoperfusion are associated with worse coagulopathy and organ function. The practice of hypotensive resuscitation would appear counterintuitive to the goals of traumatic shock resuscitation and is not supported by consistent clinical data. In addition, excessive volume resuscitation is associated with adverse clinical outcomes. Therefore, in the resuscitation of traumatic shock, it is necessary to target an appropriate balance with intravascular volume and vascular tone. It would appear logical that vasopressors may be useful in traumatic shock resuscitation to counteract vasodilation in hemorrhage as well as other clinical conditions such as traumatic brain injury, spinal cord injury, multiple organ dysfunction syndrome, and vasodilation of general anesthetics. The purpose of this article is to discuss the controversy of vasopressors in hypotensive trauma patients and advocate for a nuanced approach to vasopressor administration in the resuscitation of traumatic shock.
Sewing Machines for Socialism?
Authors: Banks Elizabeth
Published: April 2021

This article examines negotiations on aid, scholarship provision, and a hoped-for visit by former cosmonaut Valentina Tereshkova, that took place between the Committee for Soviet Women (KSZh) and the Organization for Mozambican Women (OMM) as a lens into Soviet-African interaction in the late twentieth century. Women's organizations offer a unique perspective as women's rights occupied a central place in socialism, conceptions of modernity, and African nationalist organizing. Drawing on archives, interviews, and organizational publications, the article highlights how the symbolic and pragmatic politics of these connections were woven together through the circulation of gifts. At the same time, the article draws attention to fundamental misalignment in the groups' conceptions of gender and in their ambitions for the relationship. Bound by institutional norms, the KSZh consistently offered OMM the same set of items year after year, while OMM women asked for alternative forms of support with higher material and symbolic value because they believed their relationship should be mutually determined and relevant for local conditions.
Cubitus interruptus is necessary but not sufficient for direct activation of a wing-specific decapentaplegic enhancer
Authors: Hepker Jennifer , Blackman Ronald K. , Holmgren Robert
Published: April 2021

In Drosophila, the imaginal discs are the primordia for adult appendages. Their proper formation is dependent upon the activation of the decapentaplegic (dpp) gene in a stripe of cells just anterior to the compartment boundary. In imaginal discs, the dpp gene has been shown to be activated by Hedgehog signal transduction. However, an initial analysis of its enhancer region suggests that its regulation is complex and depends upon additional factors. In order to understand how multiple factors regulate dpp expression, we chose to focus on a single dpp enhancer element, the dpp heldout enhancer, from the 3′ cis regulatory disc region of the dpp locus. In this report, we present a molecular analysis of this 358 bp wing-and haltere-specific dpp enhancer, which demonstrates a direct transcriptional requirement for the Cubitus interruptus (Ci) protein. The results suggest that, in addition to regulation by Ci, expression of the dpp heldout enhancer is spatially determined by Drosophila TCF (dTCF) and the Vestigial/Scalloped selector system and that temporal control is provided by dpp autoregulation. Consistent with the unexpectedly complex regulation of the dpp heldout enhancer, analysis of a Ci consensus site reporter construct suggests that Ci, a mediator of Hedgehog transcriptional activation, can only transactivate in concert with other factors.
longfin causes cis-ectopic expression of the kcnh2a ether-a-go-go K+ channel to autonomously prolong fin outgrowth
Authors: Stewart Scott , Le Bleu Heather K. , Yette Gabriel A. , Henner Astra L. , Robbins Amy E. , Braunstein Joshua A. , Stankunas Kryn
Published: April 2021

Organs stop growing to achieve a characteristic size and shape in scale with the body of an animal. Likewise, regenerating organs sense injury extents to instruct appropriate replacement growth. Fish fins exemplify both phenomena through their tremendous diversity of form and remarkably robust regeneration. The classic zebrafish mutant longfint2 develops and regenerates dramatically elongated fins and underlying ray skeleton. We show longfint2 chromosome 2 overexpresses the ether-a-go-go-related voltage-gated potassium channel kcnh2a. Genetic disruption of kcnh2a in cis rescues longfint2, indicating longfint2 is a regulatory kcnh2a allele. We find longfint2 fin overgrowth originates from prolonged outgrowth periods by showing Kcnh2a chemical inhibition during late stage regeneration fully suppresses overgrowth. Cell transplantations demonstrate longfint2-ectopic kcnh2a acts tissue autonomously within the fin intra-ray mesenchymal lineage. Temporal inhibition of the Ca2+-dependent phosphatase calcineurin indicates it likewise entirely acts late in regeneration to attenuate fin outgrowth. Epistasis experiments suggest longfint2-expressed Kcnh2a inhibits calcineurin output to supersede growth cessation signals. We conclude ion signaling within the growth-determining mesenchyme lineage controls fin size by tuning outgrowth periods rather than altering positional information or cell-level growth potency.
Oxygen availability as a control factor in the density-dependent regulation of protein synthesis in cell culture
Authors: Verma Desh Pal S. , Marcus A.
Published: April 2021

Dilution of a density-inhibited Arachis culture results in a 10-fold increase in capacity for protein synthesis during the first 2 h after dilution. The limitation in the density-inhibited state is not inadequate nutrition, inappropriate pH, or a diffusible inhibitor as the dilution can be carried out in medium obtained by filtration of 14-day cells. The respiratory rate of the culture increases 2-fold immediately after dilution and the ATP level increases 3-fold during the 2-h period subsequent to dilution. These observations suggest that the initial function activated by dilution is an increased availability of oxygen and that this increase in oxygen provides an increased level of ATP, finally resulting in an increased rate of protein synthesis. This idea is further supported by the finding that both the increase in cellular ATP and the acceleration of the rate of protein synthesis can be obtained in dense culture, in the absence of dilution, by maintaining the cells for 2 h under oxygen.
Microprobe measurements of calcium binding in the contractile spasmoneme of a vorticellid
Authors: Routledge L. M. , Amos W. B. , Gupta B. L. , Hall T. A. , Weis-Fogh T.
Published: April 2021

By means of an electron microprobe, the calcium content of isolated contractile organelles (spasmonemes) from the ciliate Zoothamnium was compared in extension and contraction. By using calcium buffers of different total concentrations, it was shown that the calcium in extended organelles was almost entirely due to concentration of solute during the drying of the specimen. Contracted organelles contained 17g more calcium per kg of dry mass than extended ones, and this extra calcium was bound strongly. The quantity of calcium bound in this way is consistent with the theory that the energy for contraction is derived from the chemical potential of calcium ions. Stoichiometry suggests that between 1·4 and 2·1 calcium ions become bound to each molecule of a spasmonemal calcium-binding protein.
Observations on the number of nuclei within the fibres of some red and white muscles
Authors: Burleigh I. G.
Published: April 2021

Nuclei have been enumerated in muscle fibres of different physiological properties within adult rats and rabbits. Almost invariably, and regardless of muscle type, there is a direct relationship between the cross-sectional area (or fibre breadth2) of muscle fibres and the number of nuclei within them. The one exception occurred in muscles of older rats where increased nuclear numbers do not always appear to result in broader muscle fibres.

The greater complement of nuclei in broader fibres is accompanied by larger amounts of cell substance per nucleus.

Confirming early observations in the literature, red fibres of the slow-phasic type have more nuclei than have white, fast-phasic fibres of similar breadth. These conclusions are not vitiated by differences in the number of nuclei within capillaries or in satellite cells, by differences in nuclear length or by variation in the degree to which fibres are contracted.

In respect of their complement of nuclei, and the average amount of cell substance formed per nucleus the small red fibres that occur within muscles of predominantly fast-phasic character appear to be fast- rather than slow-phasic in type.

When the number of nuclei observed per fibre is plotted against fibre cross-sectional area, the shapes of the resulting distributions suggest that estimates of muscle nuclei may be valuable not only as an index of growth potential, but of the extent to which that potential is expressed. In one muscle, the above distribution was of a form which indicated that some fibres may have formed abnormally large amounts of protein per nucleus. However, this was not adequately confirmed.

Various factors have been investigated that are relevant to the accuracy of enumerating nuclei and measuring fibre breadths.
Spermiogenesis in the fern Marsilea: Microtubules, nuclear shaping, and cytomorphogenesis
Authors: Myles Diana Gold , Hepler Peter K.
Published: April 2021

Spermiogenesis in Marsilea is a complex series of events, including the formation of a helically wound organelle coil. The coil begins to appear in early development when a multilayered structure (MLS) is formed de novo in association with a mitochondrion. The outermost layer of the MLS is a ribbon of microtubules. As the microtubules grow out from the MLS, they grow along the nuclear envelope. The nucleus elongates parallel to the longitudinal axis of the microtubule ribbon until it makes 4-5 gyres. The coil mitochondrion associated with the MLS grows until it completes approximately 9 gyres, following the path of the nucleus in its posterior gyres. The microtubule ribbon is associated with both of these organelles along their exterior edge and separates them from the developing flagellar band. This band arises from dense material that is associated with the basal bodies from early development, increases in volume, and finally condenses into a solid band, interconnecting the 100-120 basal bodies of the sperm. The flagella are distributed along the entire organelle coil.

Besides the microtubules of the ribbon, a set of cytoplasmic tubules is seen during spermiogenesis. These microtubules radiate in bundles from a region of dense nodules located near the MLS.

Late in development there is a gross rearrangement of the cytoplasm. This rearrangement begins as the outgrowth of a ring of cytoplasm from the posterior end of the sperm, and continues to grow down around the organelle coil in the anterior end, and fuses to form a bridge, enclosing the anterior end and all the flagella. This bridge fills with cytoplasm that migrates from the posterior region, including many mitochondria and ribosomes, and is finally shed by the sperm when it is released from the microspore and becomes motile.

The possible involvement of chromatin condensation and/or microtubules in nuclear morphogenesis is considered. Because much of the shaping of the nucleus occurs before bulk chromatin condensation, the possibility that it is the cause of shaping is ruled out. We postulate that microtubules are involved, not in providing the mechanical force, but as a guide along which shape formation occurs. Furthermore, microtubules of the ribbon were observed to have a close structural relationship to the condensing chromatin.
Spatial distribution of lamin A/C determines nuclear stiffness and stress-mediated deformation
Authors: Srivastava Luv Kishore , Ju Zhaoping , Ghagre Ajinkya , Ehrlicher Allen J.
Published: April 2021

While diverse cellular components have been identified as mechanotransduction elements, the deformation of the nucleus itself is a critical mechanosensory mechanism, implying that nuclear stiffness is essential in determining responses to intracellular and extracellular stresses. Although the nuclear membrane protein lamin A/C is known to contribute to nuclear stiffness, bulk moduli of nuclei have not been reported for various levels of lamin A/C. Here, we measure the nuclear bulk moduli as a function of lamin A/C expression and applied osmotic stress, revealing a linear dependence within the range of 2–4 MPa. We also find that the nuclear compression is anisotropic, with the vertical axis of the nucleus being more compliant than the minor and major axes in the substrate plane. We then related the spatial distribution of lamin A/C with submicron 3D nuclear envelope deformation, revealing that local areas of the nuclear envelope with higher density of lamin A/C have correspondingly lower local deformations. These findings describe the complex dispersion of nuclear deformations as a function of lamin A/C expression and distribution, implicating a lamin A/C role in mechanotransduction.

This article has an associated First Person interview with the first author of the paper.
Upregulation of APP endocytosis by neuronal aging drives amyloid-dependent synapse loss
Authors: Burrinha Tatiana , Martinsson Isak , Gomes Ricardo , Terrasso Ana Paula , Gouras Gunnar K. , Almeida Cláudia Guimas
Published: April 2021

Neuronal aging increases the risk of late-onset Alzheimer's disease. During normal aging, synapses decline, and β-amyloid (Aβ) accumulates intraneuronally. However, little is known about the underlying cell biological mechanisms. We studied neuronal aging using normal-aged brain and aged mouse primary neurons that accumulate lysosomal lipofuscin and show synapse loss. We identified the upregulation of amyloid precursor protein (APP) endocytosis as a neuronal aging mechanism that potentiates APP processing and Aβ production in vitro and in vivo. The increased APP endocytosis may contribute to the early endosome enlargement observed in the aged brain. Mechanistically, we showed that clathrin-dependent APP endocytosis requires F-actin and that clathrin and endocytic F-actin increase with neuronal aging. Finally, Aβ production inhibition reverts synaptic decline in aged neurons, whereas Aβ accumulation, promoted by endocytosis upregulation in younger neurons, recapitulates aging-related synapse decline. Overall, we identify APP endocytosis upregulation as a potential mechanism of neuronal aging and, thus, a novel target to prevent late-onset Alzheimer's disease.

This article has an associated First Person interview with the first author of the paper.
Ribosome quality control activity potentiates vaccinia virus protein synthesis during infection
Authors: Sundaramoorthy Elayanambi , Ryan Andrew P. , Fulzele Amit , Leonard Marilyn , Daugherty Matthew D. , Bennett Eric J.
Published: April 2021

Viral infection both activates stress signaling pathways and redistributes ribosomes away from host mRNAs to translate viral mRNAs. The intricacies of this ribosome shuffle from host to viral mRNAs are poorly understood. Here, we uncover a role for the ribosome-associated quality control (RQC) factor ZNF598 during vaccinia virus mRNA translation. ZNF598 acts on collided ribosomes to ubiquitylate 40S subunit proteins uS10 (RPS20) and eS10 (RPS10), initiating RQC-dependent nascent chain degradation and ribosome recycling. We show that vaccinia infection enhances uS10 ubiquitylation, indicating an increased burden on RQC pathways during viral propagation. Consistent with an increased RQC demand, we demonstrate that vaccinia virus replication is impaired in cells that either lack ZNF598 or express a ubiquitylation-deficient version of uS10. Using SILAC-based proteomics and concurrent RNA-seq analysis, we determine that translation, but not transcription of vaccinia virus mRNAs is compromised in cells with deficient RQC activity. Additionally, vaccinia virus infection reduces cellular RQC activity, suggesting that co-option of ZNF598 by vaccinia virus plays a critical role in translational reprogramming that is needed for optimal viral propagation.
Secreted C-type lectin regulation of neuromuscular junction synaptic vesicle dynamics modulates coordinated movement
Authors: Bhimreddy Meghana , Rushton Emma , Kopke Danielle L. , Broadie Kendal
Published: April 2021

The synaptic cleft manifests enriched glycosylation, with structured glycans coordinating signaling between presynaptic and postsynaptic cells. Glycosylated signaling ligands orchestrating communication are tightly regulated by secreted glycan-binding lectins. Using the Drosophila neuromuscular junction (NMJ) as a model glutamatergic synapse, we identify a new Ca2+-binding (C-type) lectin, Lectin-galC1 (LGC1), which modulates presynaptic function and neurotransmission strength. We find that LGC1 is enriched in motoneuron presynaptic boutons and secreted into the NMJ extracellular synaptomatrix. We show that LGC1 limits locomotor peristalsis and coordinated movement speed, with a specific requirement for synaptic function, but not NMJ architecture. LGC1 controls neurotransmission strength by limiting presynaptic active zone (AZ) and postsynaptic glutamate receptor (GluR) aligned synapse number, reducing both spontaneous and stimulation-evoked synaptic vesicle (SV) release, and capping SV cycling rate. During high-frequency stimulation (HFS), mutants have faster synaptic depression and impaired recovery while replenishing depleted SV pools. Although LGC1 removal increases the number of glutamatergic synapses, we find that LGC1-null mutants exhibit decreased SV density within presynaptic boutons, particularly SV pools at presynaptic active zones. Thus, LGC1 regulates NMJ neurotransmission to modulate coordinated movement.
Direct evidence of cellular transformation by prion-like p53 amyloid infection
Authors: Navalkar Ambuja , Pandey Satyaprakash , Singh Namrata , Patel Komal , Datta Debalina , Mohanty Bhabani , Jadhav Sachin , Chaudhari Pradip , Maji Samir K.
Published: April 2021

Tumor suppressor p53 mutations are associated with more than 50% of cancers. Aggregation and amyloid formation of p53 is also implicated in cancer pathogenesis, but direct evidence for aggregated p53 amyloids acting as an oncogene is lacking. Here, we conclusively demonstrate that wild-type p53 amyloid formation imparts oncogenic properties to non-cancerous cells. p53 amyloid aggregates were transferred through cell generations, contributing to enhanced survival, apoptotic resistance with increased proliferation and migration. The tumorigenic potential of p53 amyloid-transformed cells was further confirmed in mouse xenografts, wherein the tumors showed p53 amyloids. p53 disaggregation rescued the cellular transformation and inhibited tumor development in mice. We propose that wild-type p53 amyloid formation contributes to tumorigenesis and can be a potential target for therapeutic intervention.

This article has an associated First Person interview with the first author of the paper.
Red blood cell adhesion: III. Analysis of forces
Authors: Parsegian V. Adrian , Gingell David
Published: April 2021

The results of experiments on the adhesion of glutaraldehyde-fixed red blood cells to both polarizable metal/saline and liquid hexadecane/saline interfaces have been analysed in terms of physical forces. The results show that the electrostatic repulsions sufficient to prevent adhesion to these test surfaces are remarkably similar, and that a force-balance condition is predicted at cell-substratum separations ∼ 100 nm in 0 ·4 MM NaCl as found by interferometry. From the repulsive force the size of the attractive force can be found. If this is viewed as an electrodynamic attraction, the force coefficient is found to lie between 5 and 8 × 10−14 erg (5 and 8 × 10−21 J), a range in reasonable correspondence with measurements in physical systems.
Motive force of the migrating pseudoplasmodium of the cellular slime mould Dictyostelium discoideum
Authors: Inouye Kei , Takeuchi Ikuo
Published: April 2021

Motive forces of migrating pseudoplasmodia (slugs) of Dictyostelium discoideum were determined by application of a double-chamber method. The motive force of a whole slug was proportional to its volume, the value per unit volume being 5 ·85 × 106 dyne/cm3 (58·5 N cm-3). The motive force was independent of temperature (13·5 —26 °C) and decreased during prolonged migration. Motive force per unit volume of an anterior isolate of a slug was much larger than that of a posterior isolate, their weighted mean being approximately equal to that of a whole slug. These results agree well with the predictions previously made using a model based on analyses of migrating velocities of slugs. The motive force per unit volume of either isolate was soon regulated to reach the normal value of an intact slug after several hours of isolation, concurrently with conversion of cell types between prestalk and prespore cells. The possibility that motive force of each cell is determined by its cell type is discussed in relation to cell sorting.
Membrane recycling and endocytosis in Paramecium confirmed by horseradish peroxidase pulse-chase studies
Authors: Allen Richard D. , Fok Agnes K.
Published: April 2021

Paramecium caudatum cells were pulse-chased in horseradish peroxidase (HRP) using pulses of 30 s to follow endosome (endocytotic vesicle) formation from defaecating digestive vacuoles and 3-min pulses to follow the movement and fate of these vesicles in the cell. Endosomes formed during the 30 s in HRP are heavily labelled with HRP reaction product and are mostly flattened. Some align along microtubules that point toward the cytopharynx. Diskoidal vesicles at the cytopharynx are unlabelled in unchased cells. Cells exposed to a 3-min HRP pulse contain varied amounts of HRP-labelled diskoidal vesicles at the cytopharynx but no labelled vesicles near their closed cytoprocts. Labelled vesicles are also found aligned along the cyto-pharyngeal microtubular ribbons. Diskoidal vesicles are no longer labelled after a 47-min chase. Use of pulse-chase HRP cytochemistry supports the hypothesis that the membrane of digestive vacuoles retrieved at the cytoproct is moved along microtubular ribbons directly to the cytopharynx where the membrane enters the diskoidal vesicle pool. This membrane appears to enter neither the Golgi nor lysosomal systems in its passage. HRP reaction product is also found in vesicles near the parasomal sacs, in some secondary lysosomes and in small spherical vesicles that are probably trichocyst membrane fragments. Possibly some membrane from parasomal sacs or condensing digestive vacuoles may also enter the diskoidal vesicle pool but apparently not membrane from trichocysts.
Role of concanavalin a as an endocytic modulator in chinese hamster ovary cells
Authors: Storrie Brian , M. Maurey Karen
Published: April 2021

The effect of the lectin, concanavalin A (Con A), on pinocytic uptake and pinosome-lysosome fusion in Chinese hamster ovary (CHO) cells, a fibroblast line, was investigated. The glycosylated protein, horseradish peroxidase (HRPase), and the non-glycosylated protein, 125I-labelled bovine serum albumin ([125I]BSA), were used as endocytic tracers. Con A at high concentrations (⩾ 50 μg/ml) promoted the uptake of HRPase and inhibited the degradation of ingested HRPase. Con A inhibited the degradation of HRPase whether the two were added simultaneously or at different times to the cultures. Fusion of HRPase-positive pinosomes with secondary lysosomes was observed by electron microscopy in Con A-treated CHO cells. Con A at 200 μg/ml had no effect on either the uptake or degradation of [125I]BSA. Together these observations strongly suggest that the effects of high Con A concentrations on the uptake and degradation of HRPase are a consequence of direct complex formation between lectin and glycoprotein. Con A does not appear to have a general modulating effect on the dynamics of endocytic membrane in CHO cells.
Functional interdependence of pseudopodia in Amoeba proteus stimulated by light-shade difference
Authors: Grębecki Andrzej , Klopocka Wanda
Published: April 2021

Polytactic cells of Amoeba proteus were exposed to localised photic stimulation. When a pseudopodium is stimulated to advance, by shading it, other pseudopodia are retracted. Activation of the shaded front is the primary response, and contraction of other fronts the secondary one. When a pseudopodium is inhibited by illuminating its frontal segment, or when it is allowed to enter the bright zone in the course of migration, it slows down and stops but its eventual retraction depends on the existence of other possible directions for the endoplasmic flow. Therefore, if other active pseudopodia are lacking, the front suppressed by light cannot retreat effectively until new fronts arise in other body regions kept in shade. In all experimental situations the development of new fronts or the activation of forward flow in lateral pseudopodia precedes the contraction of the former leading pseudopodium. Also the reversal of direction of the endoplasmic streaming begins at the new front, and then it gradually extends until it reaches the former front.

The results confirm the interdependence of different pseudopodia in the same individual and they contradict the concept that pseudopodia behave as separate functional units. On the other hand, they indicate that formation of new pseudopodia should not be explained as a simple secondary effect of contraction of the older ones but, on the contrary, as a phenomenon that initiates the changes in the pattern of flow in amoeba. The general interpretation is based on this variant of the pressure-flow theory of amoeboid movement, which attributes the motive power to the contractile activity of the whole cell cortex and the steering role to events taking place in the front of the migrating cell.
Gene expression in Acetabularia: III. Comparison of stained cytosolic proteins and in vivo and in vitro translation products
Authors: Shoeman Robert L. , Neuhaus Gunther , Schweiger Hans-Georg
Published: April 2021

A comparison of stained cytosolic proteins, in vivo 80 S ribosome translation products and in vitro translation products of poly(A)+ RNA from three species of Acetabularia was performed after characterization of their molecular weights and isoelectric points via two-dimensional electrophoresis. A total of 803 stained proteins, and 121 in vivo and 77 in vitro translation products, representing the most abundant proteins in each category, were analysed. In interspecies comparisons, approximately 10% of the stained proteins were common to all three species and more than 50% were found to be species-specific. Approximately 25% of the in vivo translation products were common to all three species and more than 30% were found to be species-specific. The majority of the in vivo and in vitro translation products were detected by one or both of the other methods employed. Even though the analysis was limited to the most abundant proteins detected by each of the three methods and to one stage of development, the results suggest that the translation of some proteins is not regulated, that the in vivo translation of others, whose mRNA is present and translated in vitro, is turned off while the translation in vivo of others is enhanced relative to the total. This feature makes them candidates for stage-specific proteins. The results provide a firm basis for the extended analysis of the biological activity of heterologous messenger RNA in Acetabularia cytoplasm and for a more complete cataloguing of the mRNA population and translational activity at different stages in the development of Acetabularia.