bluuebunny/crossref_metadata_2025 huggingface dataset:
Conservation issues using discordant taxonomic and evolutionary units: a case study of the American manatee (
Authors: Lima Camilla S. , Magalhães Rafael F. , Santos Fabricio R.
Published: April 2021

The delimitation of evolutionarily significant units (ESUs) frequently results in controversy, but prioritising populations with evolutionary independence is essential for effective in situ conservation management. The American manatee (Trichechus manatus) is distributed along subtropical and tropical coastal waters from Florida (USA) to Alagoas (Brazil), and two subspecies are traditionally recognised, namely, T. m. latirostris, restricted to the Florida peninsula, and T. m. manatus, found in the remaining areas. However, this subspecific classification is not supported by genetic and morphologic evidence, which, rather, recognises two deeply differentiated populations or ESUs called Atlantic (Brazil) and Caribbean (from Venezuela to Florida). In this viewpoint paper, we compare both intraspecific divisions of T. manatus and the conservation implications. First, we used all available mtDNA evidence to test the genealogical clustering of the two American manatee ESUs by using a tree-based coalescent method. Second, we have used different models under a coalescent framework to estimate the historic gene flow among manatee populations. The analysis of the spatial distribution of mtDNA clusters confirmed the existence of the two suggested ESUs, rather than the two claimed subspecies. Furthermore, the best model to explain historic migration indicates that Brazilian manatees belong to an isolated population, whereas Florida and Caribbean populations are connected by more recent gene flow. These results have confirmed that T. manatus of the Caribbean, Gulf of Mexico and Florida belong to the same deme or Caribbean ESU, and the relatively isolated population inhabiting the Atlantic coast of Brazil belongs to the Atlantic ESU. Furthermore, both ESUs are separated by an interspecific hybrid zone (with the Amazonian manatee) located around the mouth of the Amazon River towards the Guianas coastline. The subdivision of two ESUs is also highly supported by karyotypic, morphological and ecological data, and is in clear disagreement with the traditional subspecies designations and the IUCN priorities, which manages Brazilian manatees as part of the Antillean manatee subspecies (T. m. manatus). Rather, Brazilian manatees should be considered as a full priority for conservation and require further taxonomic research; because of their deep history of isolation, they present high genetic and morphologic differentiation from all other American manatees.
Why the backfire effect does not explain the durability of political misperceptions
Authors: Nyhan Brendan
Published: April 2021

Previous research indicated that corrective information can sometimes provoke a so-called “backfire effect” in which respondents more strongly endorsed a misperception about a controversial political or scientific issue when their beliefs or predispositions were challenged. I show how subsequent research and media coverage seized on this finding, distorting its generality and exaggerating its role relative to other factors in explaining the durability of political misperceptions. To the contrary, an emerging research consensus finds that corrective information is typically at least somewhat effective at increasing belief accuracy when received by respondents. However, the research that I review suggests that the accuracy-increasing effects of corrective information like fact checks often do not last or accumulate; instead, they frequently seem to decay or be overwhelmed by cues from elites and the media promoting more congenial but less accurate claims. As a result, misperceptions typically persist in public opinion for years after they have been debunked. Given these realities, the primary challenge for scientific communication is not to prevent backfire effects but instead, to understand how to target corrective information better and to make it more effective. Ultimately, however, the best approach is to disrupt the formation of linkages between group identities and false claims and to reduce the flow of cues reinforcing those claims from elites and the media. Doing so will require a shift from a strategy focused on providing information to the public to one that considers the roles of intermediaries in forming and maintaining belief systems.
Emotion and humor as misinformation antidotes
Authors: Yeo Sara K. , McKasy Meaghan
Published: April 2021

Many visible public debates over scientific issues are clouded in accusations of falsehood, which place increasing demands on citizens to distinguish fact from fiction. Yet, constraints on our ability to detect misinformation coupled with our inadvertent motivations to believe false science result in a high likelihood that we will form misperceptions. As science falsehoods are often presented with emotional appeals, we focus our perspective on the roles of emotion and humor in the formation of science attitudes, perceptions, and behaviors. Recent research sheds light on how funny science and emotions can help explain and potentially overcome our inability or lack of motivation to recognize and challenge misinformation. We identify some lessons learned from these related and growing areas of research and conclude with a brief discussion of the ethical considerations of using persuasive strategies, calling for more dialogue among members of the science communication community.
Ligustrum sinense (Chinese privet).
Authors: Shaw Dick
Published: April 2021

A datasheet on Ligustrum sinense covering, as an economically important tree, its taxonomy, importance, silviculture, distribution, biology and ecology, uses, products and pests.
Crossover from a delocalized to localized atomic excitation in an atom–waveguide interface
Authors: Jen H H , You J-S
Published: April 2021

An atom–waveguide system, which presents one of the quantum interfaces that enable strong couplings between light and atoms, can support tightly-confined guided modes of light. In this distinctive quantum interface, we theoretically investigate the crossover from a delocalized to localized atomic excitation under long-range dipole–dipole interactions and lattice disorders. Both localization lengths of the excitation distributions and power-law scalings of dissipative von Neumann entanglement entropy show signatures of this crossover. We further calculate numerically the level statistics of the underlying non-Hermitian Hamiltonian, from which as the disorder strength increases, the gap ratio decreases and the intrasample variance increases before reaching respective saturated values. The mean gap ratio in the deeply localized regime is close to the one from Poisson statistics along with a relatively large intrasample variance, whereas in the nondisordered regime, a significant level repulsion emerges. Our results provide insights to study the non-ergodic phenomenon in an atom–waveguide interface, which can be potentially applied to photon storage in this interface under dissipations.
Electronic and optical properties of tapered tetrahedral semiconductor nanocrystals
Authors: Na Guangren , li Yawen , Wang Xiaoyu , Fu Yuhao , Zhang Lijun
Published: April 2021

The quantum confinement effect resulting from size reduction drastically alters the electronic structure and optical properties of optoelectronic materials. Quantum confinement in nanomaterials can be efficiently controlled by morphology variation combined characteristics of nanomaterials, such as their size, shape, and spatial organization. In this study, considering indium arsenide (InAs) in tetrahedral semiconductors as an example, we demonstrated the controllable morphology evolution of InAs nanostructures by tuning the growth conditions. We used the atomistic pseudopotential method to investigate the morphology-dependent electronic and optical properties of InAs nanostructures: tapered and uniform nanostructures, including the absorption spectra, single-particle energy levels, distribution and overlap integral of band-edge states, and exciton binding energies. Compared with uniform nanomaterials, a weaker quantum confinement effect was observed in the tapered nanomaterials, because of which tapered InAs nanostructures have a smaller bandgap, larger separation of photoinduced carriers, and smaller exciton binding energy. The absorption spectra of InAs nanostructures also exhibit strong morphology dependence. Our results indicate that morphology engineering can be exploited as a potential approach for modulating the electronic and optoelectronic properties of nanomaterials.
Power density improvement based on investigation of initial relative position in an electromagnetic energy harvester with self-powered applications
Authors: Peng Yan , Zhang Dong , Luo Jun , Xie Shaorong , Pu Huayan , Li Zhongjie
Published: April 2021

In this paper, we originally report a breakthrough in the power density of a novel electromagnetic energy harvester to scavenge ambient low-frequency vibration energy. The harvester adopted a configuration of alternating south- and north-pole magnet array, which causes a step-change in magnetic flux density, contributing to high electromotive force output. Through analysis of the coil configuration and the initial relative position between coils and magnets, the harvester can take full advantage of the abrupt flux density change, which enhances its output power significantly. Experimental results adequately validated the simulation analysis regarding the correlation between the initial relative position and output power, and exhibited a high output performance. Namely, the maximum average power and power density the harvester yields are 44.8 mW and 1.6

mW

c

m

−
3

, respectively, with the optimum resistance of 30 Ω at resonance under the excitation of 1 g. It took the harvester around 5 min to charge a button lithium battery up to 21%. Meanwhile, a LED array composed of 180 diodes was successfully lighted up, and a calculator was powered for around 630 s within a 20 s of charging period. This research shows great potential in the development of self-powered systems.
Rapid Nb3Sn film growth by sputtering Nb on hot bronze
Authors: Withanage Wenura K , Juliao Andre , Cooley Lance D
Published: April 2021

Nb deposited by magnetron sputtering onto hot Cu-15 wt.%Sn bronze substrates at temperatures above 700 °C achieved Nb3Sn film growth at a rate of 33 nm min−1, which was an order of magnitude faster than that achieved for deposition of Nb on bronze at low temperature followed by in situ post reaction at the same high temperatures. Tin content in the Nb3Sn films made on hot bronze was ∼26.3%, which is significantly higher than ∼24.5% obtained by post-reaction as well as for typical bulk reactions between Nb and α-bronze. The Nb3Sn lattice parameter was consistent with measured tin content and predicted elastic strain for both routes. Critical temperatures of 14 K–16 K, instead of 18 K, were consistent with elastic strain due to coefficient of thermal expansion mismatch between the Nb3Sn and bronze substrate and, for the hot-bronze samples, stress related to the growth mechanism. Films were fully coalesced and had surface roughness values <20 nm over a 100 μm2 scan. Grain structure of the Nb3Sn films produced by Nb sputtering on hot bronze resembles zone 2 in the Thornton structure-zone diagram, in contrast to the equiaxed grain structure reminiscent of microstructure observed in reacted Nb3Sn wires exhibited by the post-reaction route.
Corrigendum: The amount and type of plastics in the Baiya Beach after the Palu Bay tsunami (2021 J. Phys.: Conf. Ser. 1763 012072)
Authors: Sulistiawati D , Safir M , Putra A E , Mansyur K , Rizal A , Serdiati N , Siampa T , Ya’la Z R
Published: April 2021

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AlGaN nanowires with inverse taper for flexible DUV emitters
Authors: Hartensveld Matthew , Melanson Bryan , Liu Cheng , Zhang Jing
Published: April 2021

Deep ultraviolet (DUV) AlGaN light-emitting diodes (LEDs) are promising alternatives for production of DUV light, offering many advantages over mercury arc lamps. In this work, AlGaN nanowires with an inverse taper profile were demonstrated through a wet etching process, enabling removal of the nanowires from the growth substrate in a novel peeling process to form flexible devices. AlGaN nanowires with taper angles of ∼22° were obtained following a 70 min etch in AZ400K. Nanowire taper angle was studied as a function of etch time and nanowire top diameter. Nanowires with inverse taper were then embedded in a flexible polymer layer and removed from their growth substrate, which could enable development of high-efficiency flexible micro-LEDs. Released nanowires embedded within the polymer liftoff layer exhibit strain relaxation induced redshift due to reduction in piezoelectric polarization electric field intensity. The inverse taper structure was found to promote enhanced light extraction from the nanowire. The demonstrated flexible DUV emitters with inverse taper are shown to improve the device efficiency and allow for realization of flexible emitters through a novel fabrication process for the first time.
Generation of terahertz radiation by short laser pulses propagating in obliquely magnetized plasma
Authors: Mishra Dinkar , Sharma Pooja , Singh Saumya , Kumar Bhupesh , Jha Pallavi
Published: April 2021

This paper presents an analytical and simulation study of terahertz (THz) radiation generation using short, circularly polarized laser pulses propagating in plasma embedded in arbitrarily oriented magnetic field. Perturbation technique is used to obtain generated electric and magnetic wakefields within and behind the laser pulse. Coupling of components of the obliquely applied magnetic field with transverse and axial plasma electron velocities leads to the generation of linearly as well as elliptically polarized transverse electromagnetic radiation oscillating at THz frequency, under appropriate conditions. The amplitude of these fields and ellipticity of the elliptically polarized THz radiation can be varied with the help of the obliqueness of the external magnetic field. Analytical results are validated using VSim PIC simulation code.
Dynamic analysis of coupled composite laminated shells with elastic boundary condition using a domain decomposition method
Authors: An Kwangil , Kim Changrok , Kim Kwanghun , Kwak Songhun , Ri Kumchol , Kim Hohyok
Published: April 2021

In this paper, the free and forced vibration behavior of coupled composite laminated shell are investigated by using a domain decomposition method under the elastic boundary condition. The coupled shell structure is combined in the form of a double curved shell-cylindrical shell-double curved shell, and the double curved shells at both ends are combined with the cylindrical shell upside down (figure 1). The double curved shell contains the elliptical, paraboloidal and hyperbolical shells. multi-segment partitioning technique is employed to establish the theoretical model based on the first-order shear deformation theory (FSDT). Regardless of the shell types and boundary conditions, the displacement functions of each shell are expended by the orthogonal ultraspherical polynomials in the meridional direction, and by the standard Fourier series in the circumferential direction. The boundary and continue conditions are generalized by the artificial spring technology. The convergence study and numerical comparison with finite element method (FEM) demonstrates that the proposed method has good reliability and accuracy to analyze the dynamic characteristics of the coupled composite laminated shell. The effects of material properties, geometric dimension, boundary condition and external force on the coupled composite laminated shell structure are proposed with some numerical results.
Democratic Backsliding, Subsidized Speech, and the New Majoritarian Entrenchment
Authors: Shinar Adam
Published: April 2021

This Article argues that democratic backsliding is operationalized through selective government funding of private speech. Subsidized speech can leverage the government’s voice while silencing or diminishing voices that seek to challenge the government’s message or create the background conditions for critical faculties. This leveraging, in turn, serves to entrench the power of the political majority, further insulating it from the processes of democratic change.

Despite the voluminous literature on free speech, few discuss the problem of subsidized speech, even though it plays an ever-growing role in the formation of public discourse and public opinion. Accordingly, the Article makes three contributions. First, the Article examines three jurisdictions (Israel, Hungary, and Poland), arguing that the strategic use of subsidized speech is particularly prevalent in countries that are experiencing some version of “democratic backsliding.” The commonalities between these countries are no accident, for the motivation is the same: increasing governmental domination of civil society.

Second, the Article departs from the extant approaches that identify subsidized speech as a problem for free speech or equality, by situating subsidized speech as a structural problem for democracy: majoritarian entrenchment. Although democracies have mechanisms to prevent entrenchment of the current political majority, those focus on elections and related aspects. Entrenchment, however, is not confined to these contexts. The Article thus extends the problem of entrenchment to the speech context.

Third, the Article introduces and develops the “anti-entrenchment” principle. When the government seeks to entrench its power through funding decisions, the anti-entrenchment principle is triggered. Applying the anti-entrenchment principle can have far-reaching consequences, for it may require the government to subsidize precisely the speech it rejects.
Political Involvement of Social Workers in Majority and Minority Groups: Comparison of Palestinians-Israeli and Jewish-Israeli
Authors: Darawshy Neveen Ali-Saleh , Boehm Amnon , Boehm-Tabib Esther
Published: April 2021

Previous research has examined the political involvement of social workers and their encouragement of their clients to be politically active. However, few studies have investigated this topic by comparing minority and majority groups. The current research focused on the political involvement of social workers themselves, their encouragement of clients to be politically involved, and the types of political involvement they engage in. Differences in these aspects between two groups—minority (Palestinian–Israeli) and majority (Jewish–Israeli) social workers—were also examined. One hundred and sixty-five social workers in northern Israel (Palestinian Israelis and Jewish Israelis), randomly selected from social service departments, completed self-report questionnaires. The results revealed low levels of political involvement across groups, with more encouragement of clients to be politically involved than political involvement of social workers themselves. Social workers engaged more in negotiating, as consensus-type, than in the other types of activity examined. According to their reports, the Palestinian-Israeli social workers were involved more than their Jewish-Israeli colleagues in political action and in encouraging their clients to be involved. Future training programmes should highlight the importance of political activity amongst Israeli social workers, encouraging future practitioners to participate in direct and indirect involvement and develop their sense of political efficacy.
Governmental and Non-Governmental Community Practice—What’s the Difference?
Authors: Itzhaki-Braun Yael , Feldman Guy , Frankenburg Ruth , Karassik Daniel , Schreiber Keren
Published: April 2021

The social work profession emphasises the importance of social workers’ involvement in community practice, which aims to promote social policy and social change via peoples’ organising and acting. The current qualitative study compares between the perceptions and everyday experiences of governmental and non-governmental community social workers. Drawing on in-depth interviews with twenty-six community social workers in the public social services and non-governmental organisations in Israel, findings highlight similarities and differences along three main themes: (i) community social workers’ constructions of their professional role, referring to soft community practice verus radical community practice and to aspects of influence; (ii) the tension between the professional freedom they hold and the limitations imposed on them; and (iii) professional position within the organisation and the field of community social work. We discuss these findings in light of the theoretical perspectives of perception of organisational politics and emotional labour. Implications to community practice are outlined.
Prefrontal Plasticity after a 3-Month Exercise Intervention in Older Adults Relates to Enhanced Cognitive Performance
Authors: Soshi Takahiro , Andersson Michael , Kawagoe Toshikazu , Nishiguchi Shu , Yamada Minoru , Otsuka Yuki , Nakai Ryusuke , Abe Nobuhito , Aslah Adibah , Igasaki Tomohiko , Sekiyama Kaoru
Published: April 2021

This study examined exercise intervention effects on older adults’ brain structures and function. Brain data were analyzed from 47 healthy adults between 61 and 82 years of age who, in a previous study, showed cognitive improvement following a 3-month intervention. The participants were assigned to a motor exercise intervention group (n = 24), performing exercise training programs for a 12-week period, or a waiting control group (n = 23), abstaining from any exercise program. Structural analysis of the frontal cortex and hippocampus revealed increased gray matter volume and/or thickness in several prefrontal areas in the intervention group and reduced hippocampal gray matter volume in the control group. Importantly, the volume increase in the middle frontal sulcus in the intervention group was associated with a general cognitive improvement after the intervention. Functional analysis showed that the prefrontal functional connectivity during a working memory task differently changed in response to the intervention or waiting in the two groups. The functional connectivity decreased in the intervention group, whereas the corresponding connectivity increased in the control group, which was associated with maintaining cognitive performance. The current longitudinal findings indicate that short-term exercise intervention can induce prefrontal plasticity associated with cognitive performance in older adults.
The Evolution and Distribution of Pneumococcal Serotypes in Adults Hospitalized With Community-Acquired Pneumonia in Spain Using a Serotype-Specific Urinary Antigen Detection Test: The CAPA Study, 2011–2018
Authors: Torres Antoni , Menéndez Rosario , España Pedro Pablo , Fernández-Villar Jose Alberto , Marimón José María , Cilloniz Catia , Méndez Raúl , Egurrola Mikel , Botana-Rial Maribel , Ercibengoa María , Méndez Cristina , Cifuentes Isabel , Gessner Bradford D ,   CAPA Study Group, Torres A , Cilloniz C , Ceccato A , San José A , Bueno L , Marco F , Menéndez R , Méndez R , Amara I , López Hontangas J L , Montull B , Gimeno A , Gil A , Piro A , González P , Zaldivar E , Feced L , Latorre A , España P P , Egurrola M , Uranga A , Martínez de la Fuente A P , Artaraz A , Pérez N , Fernández-Villar A , Botana-Rial M , Vasallo F , Priegue A , Marimón J M , Pérez-Trallero E , Ercibengoa M , Méndez C , Cifuentes I , Balseiro C , Del Amo M , García A , Sáez J , Perianes A , Díaz A , Garijo E , Fernández E , Martínez J , Casassas R , Samaniego M L
Published: April 2021

Background

Spain introduced the 13-valent pneumococcal conjugate vaccine (PCV13) in the childhood National Immunization Program in 2015–2016 with coverage of 3 doses of 94.8% in 2018. We assessed the evolution of all pneumococcal, PCV13 vaccine type (VT), and experimental PCV20-VT (PCV13 + serotypes 8, 10A, 11A, 12F, 15B, 22F, 33F) hospitalized community-acquired pneumonia (CAP) in adults in Spain from 2011–2018.

Methods

A prospective observational study of immunocompetent adults (≥18 years) admitted to 4 Spanish hospitals with chest X-ray–confirmed CAP between November 2011 and November 2018. Microbiological confirmation was obtained using the Pfizer serotype-specific urinary antigen detection tests (UAD1/UAD2), BinaxNow test for urine, and conventional cultures of blood, pleural fluid, and high-quality sputum.

Results

Of 3107 adults hospitalized with CAP, 1943 were ≥65 years. Underlying conditions were present in 87% (n = 2704) of the participants. Among all patients, 895 (28.8%) had pneumococcal CAP and 439 (14.1%) had PCV13-VT CAP, decreasing from 17.9% (n = 77) to 13.2% (n = 68) from 2011–2012 to 2017–2018 (P = .049). PCV20-VT CAP occurred in 243 (23.8%) of those included in 2016–2018. The most identified serotypes were 3 and 8. Serotype 3 accounted for 6.9% (n = 215) of CAP cases, remaining stable during the study period, and was associated with disease severity.

Conclusions

PCV13-VT caused a substantial proportion of CAP in Spanish immunocompetent adults 8 years after introduction of childhood PCV13 immunization. Improving direct PCV13 coverage of targeted adult populations could further reduce PCV13-VT burden, a benefit that could be increased further if PCV20 is licensed and implemented.
COVID-19 Diagnostic System Using Medical Image Classification and Retrieval: A Novel Method for Image Analysis
Authors: Alrahhal Maher , K P Supreethi
Published: April 2021

With the rapid increase in the number of people infected with COVID-19 disease in the entire world, and with the limited medical equipment used to detect it (testing kit), it becomes necessary to provide another detection method that mainly relies on Artificial Intelligence and radiographic Image Analysis to determine the disease infection. In this study, we proposed a diagnosis system that detects the COVID-19 using chest X-ray or computed tomography (CT) scan images knowing that this system does not eliminate the reverse transcription-polymerase chain reaction test but rather complements it. The proposed system consists of the following steps, starting with extracting the image’s features using Visual Words Fusion of ResNet-50 (deep neural network) and Histogram of Oriented Gradient descriptors based on Bag of Visual Word methodology. Then training the Adaptive Boosting classifier to classify the image to COVID-19 or NOTCOVID-19 and finally retrieving the most similar images. We implemented our work on X-ray and CT scan databases, and the experimental results demonstrate the effectiveness of the proposed system. The performance of the classification task in terms of accuracy was as follows: 100% for classifying the input image to X-ray or CT scan, 99.18% for classifying X-ray image to COVID-19 or NOTCOVID-19 and 97.84% for classifying CT scan to COVID-19 or NOTCOVID-19.
Children’s Experiences with School Lockdown Drills: A Pilot Study
Authors: Bonanno Rebecca , McConnaughey Susan , Mincin Jenny
Published: April 2021

In response to the threat of school shootings, lockdown drills have become commonplace in K–12 schools throughout the United States. Educators, parents, and others continue to debate the potential disruptive and traumatizing impact drills have on children. A small number of quantitative studies have examined the effects of lockdown drills on students’ perceptions of safety, preparedness for crises, and fear and anxiety. Less is known about children’s actual lived experiences of lockdown drills. This pilot child-centered qualitative study explored how children ages eight to 11 thought and felt about their experiences of school lockdown drills. Fear was found to be their common emotional response to the drill and, to a lesser extent, so were feelings of safety, annoyance, and excitement. Although children were found to have good understanding of what to do in lockdown drills, they were not always clear about what the purpose of the drills was and what threats the drills were intended to protect against. These findings support professional and advocacy groups’ recommendations for planning and implementing lockdown drills and offer original recommendations from children’s points of view on ways to mitigate negative outcomes of drills for students.
Understanding women’s perspectives and information needs about shared follow-up care for early breast cancer: a qualitative study
Authors: White Victoria , Der Vartanian Carolyn , Tansley Fiona , Ugalde Anna
Published: April 2021

Background

Shared breast cancer follow-up care involving a breast cancer specialist and a general practitioner (GP) has been demonstrated to be effective, yet barriers to participation in this model by women remain. This study explores the responses of women who recently finished active treatment for early breast cancer (EBC) to a proposed model of shared follow-up care to understand the type of information needed to support participation.

Methods

Qualitative study based on focus groups with women with EBC in the early stage of follow-up care from across metropolitan, regional and rural settings in Australia. Discussions were transcribed and thematic analysis is undertaken.

Results

Four focus groups were conducted, involving 31 women aged between 32 and 78 years. The discussion focused on two topics. In the first topic ‘Current experiences of follow-up care’, two themes emerged: (i) follow-up as a continuation of active treatment; (ii) GPs involvement in care during active treatment influence attitudes to shared follow-up care. In the second topic area ‘Perceptions of shared follow-up care’ four themes emerged: (i) a need for evidence regarding model effectiveness; (ii) choice; (iii) concerns regarding capacity and capability of GPs to deliver care and (iv) the need for clear communication between GPs, specialists and women.

Conclusions

Women need information regarding the evidence for the effectiveness of shared follow-up care to assure them it does not pose a risk to their health outcomes. Clear descriptions of GP and specialist roles and the opportunity to jointly decide participation is essential for the model to be adopted.
The boom and bust of the aphid’s essential amino acid metabolism across nymphal development
Authors: Pers Daniel , Hansen Allison K
Published: April 2021

Within long-term symbioses, animals integrate their physiology and development with their symbiont. In a model nutritional mutualism, aphids harbor the endosymbiont, Buchnera, within specialized bacteriocyte cells. Buchnera synthesizes essential amino acids (EAAs) and vitamins for their host, which are lacking from the aphid’s plant sap diet. It is unclear if the aphid host differentially expresses aphid EAA metabolism pathways and genes that collaborate with Buchnera for the production of EAA and vitamins throughout nymphal development when feeding on plants. It is also unclear if aphid bacteriocytes are differentially methylated throughout aphid development as DNA methylation may play a role in gene regulation. By analyzing aphid gene expression, we determined that the bacteriocyte is metabolically more active in metabolizing Buchnera’s EAAs and vitamins early in nymphal development compared to intermediate or later immature and adult lifestages. The largest changes in aphid bacteriocyte gene expression, especially for aphid genes that collaborate with Buchnera, occurred during the 3rd to 4th instar transition. During this transition, there is a huge shift in the bacteriocyte from a high energy “nutrient-consuming state” to a “recovery and growth state” where patterning and signaling genes and pathways are upregulated and differentially methylated, and de novo methylation is reduced as evidenced by homogenous DNA methylation profiles after the 2nd instar. Moreover, bacteriocyte number increased and Buchnera’s titer decreased throughout aphid nymphal development. These data suggest in combination that bacteriocytes of older nymphal and adult lifestages depend less on the nutritional symbiosis compared to early nymphal lifestages.
SEXUAL INCOMPATIBILITY FACTORS AND SOMATIC RECOMBINATION IN SCHIZOPHYLLUM COMMUNE
Authors: Frankel Carl , Ellingboe Albert H
Published: April 2021

Two sets of diploid cultures of S. commune were observed for sectoring due to haploidization or recombination. Each set consisted of compatible and common-AB diploids otherwise almost isogenic. One of the sets included two compatible diploids with a large proportion of dikaryotic cells. The sectors were isolated and analysed for evidence of aneuploidy and frequent crossing over to determine whether they arose via mitotic or meiotic-like events. It was found that the recombination process in both common-AB and compatible diploids was predominantly mitotic. However, the compatible diploids which developed a high frequency of dikaryotic components gave some evidence of meiotic-like activity. Thus, compatible mating-type factors are necessary for dikaryosis, but not sufficient in themselves to produce it. In compatible mycelia where dikaryosis does occur, meiotic-like recombination may also occur. It is proposed that both lapse into the dikaryotic state, and meiotic-like recombination was induced by different genes under control of the incompatibility factors. Dikaryosis and meiosis are thus seen as tandem phenomena, neither causal of the other but both induced by action of compatible mating-type factors.
THE CYTOGENETICS OF A RECESSIVE VISIBLE MUTANT ASSOCIATED WITH A DEFICIENCY ADJACENT TO THE NOTCH LOCUS IN DROSOPHILA MELANOGASTER
Authors: Keppy D O , Welshons W J
Published: April 2021

The recessive visible faswb allele in Drosophila is an interband deletion between salivary band 3C5, 6 and 7. Heterozygosity for the deletion does not suppress recombination between faswb and mutant sites at Notch adjacent to it.—Df(1)w67k30, deficient for salivary bands 3C2 to 6, is to the left of faswb. By crossing over within the homologous bit of interband retained in w67k30 and faswb, the two deficiencies can be linked. Cytologically, 3C7, "fused" to 3C5, 6 in faswb, becomes "fused" to 3C1 when the two are coupled. In the double deletion, the recessive visible phenotype of the faswb "allele" is suppressed. Both w67k30 and faswb can be recovered by uncoupling the two deficiencies.—The data suggest that the mutant faswb does not represent a lesion at Notch; the entire gene or locus seems to be present. The interband deletion in faswb has secondarily moved an intact Notch locus to a foreign environment that interferes with its normal function. When faswb is linked to w67k30, the interference is eliminated and normal Notch functions resume.—The position of Notch on the salivary gland chromosome is reviewed in relation to the information obtained in these experiments.
CONTROL OF GALACTOSYL DIGLYCERIDES IN WHEAT ENDOSPERM BY GROUP 5 CHROMOSOMES
Authors: Hernandez-Lucas C , De Caleya R Fernandez , Carbonero Pilar , Garcia-Olmedo F
Published: April 2021

Lower levels of monogalactosyl diglyceride (MGDG) and digalactosyl diglyceride (DGDG) have been found in tetraploid wheats as compared with those in hexaploid wheats. The same difference has been found between hexaploid cultivars and tetraploid lines derived from them by D genome extraction. A lower level of MGDG and DGDG is also present in Triticum carthlicum (AABB) as compared with Aegilops squarrosa (DD) or with the synthetic T. spelta (AABBDD) obtained from them. Analysis of the appropriate nullitetrasomic and ditelosomic lines indicates that a gene or genes located in the short arm of chromosome 5D are responsible for the observed difference and that group 5 chromosomes can be ranked as to their influence on the MGDG and DGDG levels in the order 5B > 5D > 5A and 5D > 5B > 5A, respectively. These results further support our previous identification of DGDG as the lipid factor responsible for petroleum ether solubility of lipopurothionins. Since DGDG contributes to baking quality by improving the retention of fermentation gases, the present observations imply that the difference in bread-making quality between the two types of wheat is not due only to proteins contributed by the D genome.
EVIDENCE FOR NEWLY INDUCED GENETIC ACTIVITY RESPONSIBLE FOR MALE RECOMBINATION INDUCTION IN DROSOPHILA MELANOGASTER
Authors: Slatko Barton E
Published: April 2021

The T-007 second chromosomal line of Drosophila melanogaster, previously shown to contain a major element, Mr, responsible for male recombination induction, also contains the genetic capability to induce male recombination activity into (nonhomologous) third chromosomes. This newly induced male recombination activity maps to the centromeric region of two third-chromosome lines that were subjected to mapping experiments. The ability of these third chromosome lines to induce male recombination accounts for previous observations concerning the ability of Mr  + genotypes (derived from Mr/Mr  + heterozygous females) to induce male recombination for only a few generations, when only second chromosomes were selected and backcrossed. The occurrence of this effect, and a similar effect induced in the homologue of T-007, suggests a possible explanation of how natural populations of D. melanogaster have come to contain such high frequencies of these "male recombination" second and third chromosomes, despite their numerous deleterious effects.
GENETICAL AND BIOCHEMICAL CHARACTERIZATION OF QA-3 MUTANTS AND REVERTANTS IN THE QA GENE CLUSTER OF NEUROSPORA CRASSA
Authors: Case Mary E , Pueyo Carmen , Barea J Lopez , Giles Norman H
Published: April 2021

The qa-3 gene, one of the four genes in the qa gene cluster, encodes quinate (shikimate) dehydrogenase (quinate: NAD oxidoreductase, ER 1.1.1.24), the first enzyme in the inducible quinic acid catabolic pathway in Neurospora crassa. Genetic analyses have localized 26 qa-3 mutants at 11 sites on the qa-3 genetic map on the basis of prototroph frequencies. Certain mutants, e.g., 336-3-10 and 336-3-3, are located at opposite ends of the qa-3 gene. Data from four-point crosses (qa-1S mutant 124 x five different qa-3 mutants in triple mutants qa-3, qa-4, qa-2) indicate the following orientation of the qa-3 gene within the qa cluster: qa-1, qa-3 mutant 336-3-10 ("left" end) qa-3 mutant 336-3-3 ("right" end), qa-4, qa-2. Ultraviolet-induced revertants have been obtained from 14 of the qa-3 mutants. The revertable mutants fall into two major classes: those that revert by changes either at the same site or at a second site within the qa-3 gene, and those that revert by unlinked suppressor mutations. The intragenic revertants can be further distinguished by quantative and/or qualitative differences in their quinate dehydrogenase activities. Some revertants with activities either equivalent to or less than wild type produce a thermostable enzyme, and others an enzyme which is thermolabile in vitro at 35°. A concentration of quinic acid or shikimic acid as low as 50 μm protects the enzyme markedly from heat inactivation. The genetic organization and the orientation of the qa-3 gene are discussed with respect to its direction of transcription and to the possible localization of a promoter (initiator) region(s) within the qa gene cluster.
MITOTIC RECOMBINATION IN THE HETEROCHROMATIN OF THE SEX CHROMOSOMES OF DROSOPHILA MELANOGASTER
Authors: Ripoll P , Garcia-Bellido A
Published: April 2021

The frequency of spontaneous and X-ray-induced mitotic recombination involving the Y chromosome has been studied in individuals with a marked Y chromosome arm and different XY compound chromosomes. The genotypes used include X chromosomes with different amounts of X heterochromatin and either or both arms of the Y chromosome attached to either side of the centromere. Individuals with two Y chromosomes have also been studied. The results show that the bulk of mitotic recombination takes place between homologous regions.
CHROMOSOMAL HOMOLOGY OF RABBIT (ORYCTOLAGUS CUNICULUS) LINKAGE GROUP VI WITH RODENT SPECIES
Authors: Fox R R , Van Zutphen L F M
Published: April 2021

Homologous portions of linkage group (LG) VI in the rabbit Oryctolagus cuniculus, chromosome 8 in Mus musculus, and LG V of Rattus norvegicus have been observed. These linkage groups in Oryctolagus and Mus contain the extension locus (e), where recessive alleles are known in many species. Preliminary linkage data have added new loci to linkage group VI of the rabbit, revised the order and map distances on the linkage map, and by comparison with rodent species have strengthened the homology of LG VI in the rabbit with chromosome 8 of the mouse and with LG V of the rat. LG VI now contains five loci with the following order and intervening map distances: Es-1, Es-2 complex—6.3 ± 2.1 cM—Est-1, Est-2 complex—18.5 ± 3.7 cM—e.
MUTATIONAL EVENTS IN THE TRIPLO- AND HAPLO-LETHAL REGION (83DE) OF THE DROSOPHILA MELANOGASTER GENOME
Authors: Roehrdanz Richard L , Lucchesi John C
Published: April 2021

The Drosophila melanogaster genome contains a single region (at 83DE on the polytene chromosome map) for which both heterozygous deficiency and heterozygous duplication are inviable. Seven EMS-induced mutations have been recovered that are viable in combination with a duplication of this region. Two classes of mutations are reported: (1) Mutations that allow survival of flies with either a duplication or a normal third chromosome. These mutations retain Ki, a closely linked marker on the mutagenized chromosome. They fail to complement, and one has been mapped to the vicinity of 83DE. (2) Mutations that allow survival only in heterozygous combination with a duplication and have lost the Ki marker. These mutations represent new deletions of the dose-sensitive information. The possible structural organization of the 83DE region is discussed in light of these two classes of mutations.
CLASSIFICATION OF NORMAL AND MALE-STERILE CYTOPLASMS IN MAIZE. I. ELECTROPHORETIC ANALYSIS OF VARIATION IN MITOCHONDRIALLY SYNTHESIZED PROTEINS
Authors: Forde B G , Oliver R J C , Leaver C J , Gunn R E , Kemble R J
Published: April 2021

Male-sterile cytoplasms of maize have previously been classified into three groups (T, S and C) according to their fertility ratings in various inbred backgrounds. In earlier studies, mitochondria from three male-sterile cytoplasms, representing each of these three groups, have been found to synthesize characteristic variant polypeptides that distinguish them from each other and from those of normal (N) cytoplasm. In order to determine the extent of cytoplasmic variation, we have now analyzed the translation products of mitochondria from 28 additional cytoplasmic sources. The results show that on this basis 18 of the cytoplasms are identical to the USDA (S) cytoplasm, three are identical to the Texas (T) cytoplasm and two are identical to the C cytoplasm. The five remaining cytoplasms are indistinguishable from normal, malefertile (N) cytoplasm. Our classification of the cytoplasms is in general agreement with those based on fertility restoration. However, of three cytoplasms that have previously remained unclassified, two (B and D) have now been assigned to the S group and one (LF) to the N group. No heterogeneity in mitochondrial translation products was detected within the normal or any of the three male-sterile groups. The usefulness of the analysis of mitochondrial translation products as a method for classifying normal and male-sterile cytoplasms is discussed.
GENE FLOW AND THE GEOGRAPHICAL DISTRIBUTION OF A MOLECULAR POLYMORPHISM IN DROSOPHILA PSEUDOOBSCURA
Authors: Jones J S , Bryant S H , Lewontin R C , Moore J A , Prout T
Published: April 2021

This paper discusses the relation between the geographical distribution of an enzyme polymorphism and population structure in Drosophila pseudoobscura. California populations of this species living in very different montane and lowland habitats separated by several kilometers are similar to each other in the frequency of an esterase allele. Previous estimates suggest that gene flow is too limited to account for this homogeneity of genetic structure, so that it must reflect some balancing force of natural selection. We show, however, that dispersal over unfavorable habitats is much greater than earlier supposed. Isolated populations of D. pseudoobscura separated by 15 km from other populations are subject to large amounts of immigration. This is shown by changes in the seasonal abundance of this species and in the annual pattern of lethal alleles in such populations. The genetic structure of an experimentally perturbed isolated population in an oasis returned to normal within a single year, suggesting that such populations are ephemeral and that the oasis is subject to annual recolonization by distant migrants. Direct assessment of marked flies shows that they can move at least 10 km in 24 hours over a desert. Such extensive gene flow may help explain the distribution of the esterase allele, and is relevant to the high level of molecular polymorphism and its general lack of geographic differentiation throughout the range of D. pseudoobscura.
SPONTANEOUS MITOTIC RECOMBINATION AND EVIDENCE FOR AN X-RAY-INDUCIBLE SYSTEM FOR THE REPAIR OF DNA DAMAGE IN DROSOPHILA MELANOGASTER
Authors: Kennison James A , Ripoll Pedro
Published: April 2021

Spontaneous mitotic recombination in the left arm of chromosome 3 was examined in both unirradiated control flies and sibs irradiated early in development by determining the sizes and frequencies of multiple-wing-hair (mwh) clones in the wing blade of heterozygous mwh/+ flies. Approximately 16% of the spontaneous mwh clones arise from events generating cells with normal division rates. The remaining 84% result from events generating cells with an average cell division rate one-third that of the surrounding cells; these are thought to result from events that generate aneuploid cells. Such clones probably arise from a failure correctly to repair spontaneous DNA damage. The frequency of spontaneous events late in development decreases significantly after irradiation as much as 150 hours earlier in development. The suppression of spontaneous events decreases with a longer period of time between irradiation and the final cell divisions in the wing blade. These results suggest the existence of a repair system for DNA damage in Drosophila that is induced by irradiation. The decrease in effect with time following irradiation could result from slow degradation or dilution by subsequent cell growth and division.
Multitechnology characterization of an unusual surface rupturing intraplate earthquake: the ML 5.4 2019 Le Teil event in France
Authors: Vallage A , Bollinger L , Champenois J , Duverger C , Trilla A Guilhem , Hernandez B , Pichon A Le , Listowski C , Mazet-Roux G , Menager M , Pinel-Puysségur B , Vergoz J
Published: April 2021

Metropolitan France is a region of slow tectonic deformation with sparse seismicity. On 11 November 2019, the ML 5.4 Le Teil earthquake became the largest seismic event recorded in the last 16 yr. This event was recorded by the national seismic networks and also by a wide variety of other geophysical techniques including infrasound and InSAR measurements. These complementary technologies offer the opportunity to investigate in detail the earthquake source characteristics and the associated ground motion attenuation. Both seismic waveform inversions and InSAR interferogram reveal a shallow rupture on a reverse fault with an associated moment magnitude of 4.8–4.9. Infrasound signals also provide fast evidences pointing towards the area of ground surface displacements, which coincides with La Rouvière fault, in the Cévennes fault system, known as a formerly active normal fault during the Oligocene. The very significant amount of seismic records also helps towards validating the GMPE laws available for the region. This multitechnology characterization documents the kinematics of this rare example of shallow intraplate fault reactivation.