bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of vapour-exchange methods for predicting hourly twig fuel moisture contents of larch and birch stands in the Daxinganling Region, China
Authors: Yu Hongzhou , Shu Lifu , Yang Guang , Deng Jifeng
Published: April 2021

The Daxinganling Region, in Heilongjiang Province, China, has experienced considerable losses to forest resources owing to a recent increase in forest fire frequency. This necessitates the predictions of fire behaviour in this region, which requires assessment of fuel moisture content (FMC) at appropriate space and time intervals. Here, we compare and extrapolate results of vapour-exchange methods for predicting hourly moisture contents of downed wood. The FMC of larch and birch twig fuels was measured at 1-h intervals at different slope positions with respect to meteorological factors. The twigs were categorised based on diameter and degree of decay. The Nelson and Simard methods (which consider equilibrium moisture content and the associated time lag) and direct regression method (which allows direct attainment of the FMC) were used. Both Nelson and Simard methods predicted hourly twig moisture content more accurately than the direct regression method. The Simard method was the most accurate, with the lowest mean absolute error and mean relative error as well as relatively small variation coefficients based on results of the extrapolation analysis. Further, the resulting models applied to needle-leaved and lightly decomposed fuels performed better than for the broad-leaved and badly decomposed fuels on evaluation parameters.
Parallel evolution of UbiA superfamily proteins into aromatic
O
-prenyltransferases in plants
Authors: Munakata Ryosuke , Olry Alexandre , Takemura Tomoya , Tatsumi Kanade , Ichino Takuji , Villard Cloé , Kageyama Joji , Kurata Tetsuya , Nakayasu Masaru , Jacob Florence , Koeduka Takao , Yamamoto Hirobumi , Moriyoshi Eiko , Matsukawa Tetsuya , Grosjean Jérémy , Krieger Célia , Sugiyama Akifumi , Mizutani Masaharu , Bourgaud Frédéric , Hehn Alain , Yazaki Kazufumi
Published: April 2021

Significance

Plants produce approximately 300
O
-prenylated aromatics, with their
O
-prenyl moieties often being crucial to their bioactivities. This study identified a gene from grapefruit encoding an aromatic
O
-prenyltransferase (
O-
PT) belonging to the UbiA superfamily. The
O
-PT was shown responsible for the biosynthesis of pharmaceutically active
O
-prenylated coumarins that cause grapefruit–drug interactions, an adverse effect disturbing the pharmacokinetics of more than 85 medications. Another UbiA
O
-PT for coumarins was isolated from
Angelica keiskei
, an apiaceous medicinal plant. Phylogenetic analysis of the rutaceous and apiaceous
O
-PTs suggested that aromatic
O
-prenylation activity emerged in parallel in these distant plant taxa. The molecular evolution of aromatic
O
-PTs from plant UbiA proteins may aid citrus breeding and a synthetic biology approach to bioactive
O
-prenylated coumarins.
Development of a small-scale commercial fish farm in the Ashanti Region of Ghana: a case study of Mr. Poku Gyinaye of Bosomtwi Integrated Aqualife Village.
Authors: Agbo Nelson
Published: April 2021

This case study documents the development of a small-scale fish farm in an attempt to highlight the efforts of a fish farmer (Mr. Poku Gyinaye, a former Fisheries officer) to establish a commercial fish farm in the Ashanti Region of Ghana. Accounts of the facilities, technology and management practices used by the farmer are described as well as his profile. The objectives of the farmer to undertake such a project were to produce fish seed for fish farmers to help them improve fish production, provide practical aquaculture training for prospective fish farmers and access to recreational fisheries for both local and foreign tourists. At the time of writing (by May 2009), Mr. Gyinaye has almost completed setting up the hatchery and has three large ponds for recreational fishing. He also has plans to start a public aquarium on the site. The main activities on his farm centre on Oreochromis niloticus and Clarias gariepinus fingerling production. He intends to stock his recreational ponds with indigenous predatory fishes.
Artemia cyst production in salt pans of the Mekong Delta, Vietnam.
Authors: Nguyen Thi Hong Van , Nguyen Van Hoa , Nguyen Thi Ngoc Anh
Published: April 2021

The Mekong Delta in south Vietnam has a long coastline with the provinces of Ben Tre, Kien Giang, Long An, Minh Hai, Soc Trang, Tien Giang and Tra Vinh. Traditional salt production is the major source of income for most of the local farmers who live along the coastline, despite the low and unstable price of salt. The introduction of Artemia (brine shrimp) from San Francisco Bay, USA, into the Mekong Delta salt pans, especially in Soc Trang and Bac Lieu provinces, opened a new trend in diversification of aquaculture species to create a better income source for local farmers. In Bac Lieu and Soc Trang provinces, Artemia cyst production is the preferred activity. Normally, they are stocked in salt pans from crystallizer to evaporation areas, even in reservoir areas where the salinity can be maintained at more than 70 ppt. The culture period lasts 5-6 months in the dry season and yields vary from 40 to 150 kg cysts ha-1(in wet weight) per crop, depending on locality, culture technique, and experience of Artemia farmers.
Morinda citrifolia (Indian mulberry).
Authors: Rojas-Sandoval Julissa
Published: April 2021

M. citrifolia is a shrub or small tree that in recent years has attained significant economic importance worldwide due to the great variety of health and cosmetic products made from its leaves and fruits. Consequently, it has been extensively introduced in cultivation and can be found cultivated and naturalized across tropical and subtropical regions of the world (Groenendijk, 1991; Nelson, 2006; Orwa et al., 2009; USDA-ARS, 2017). Currently, M. citrifolia is listed as invasive in Cuba, Costa Rica, the Dominican Republic and Haiti (Kairo et al., 2003; Chacon and Saborio, 2012, Oviedo Prieto et al., 2012). M. citrifolia is a species that can tolerate and thrive in very harsh conditions. It is well adapted to a wide range of environmental conditions and soil types. It can grow in infertile, acidic, and alkaline soils, and in areas with climates ranging from very dry to very wet. It is also tolerant to fire, waterlogging, wind, shaded conditions (>80% shade) and salt spray (Francis, 2004; Nelson, 2006; PROTA, 2017). For instance, M. citrifolia is one of the first plants to colonize harsh waste areas or lava flows on islands across the Pacific region and is also one of the few species that can thrive beneath the canopy of the allelopathic tree Casuarina equisetifolia (Nelson, 2006). Additionally, M. citrifolia has a deep taproot and an extensive and aggressive root system and once established it is very persistent and difficult to eradicate. Seeds have a distinct air chamber and can retain viability even after floating in water for months, facilitating the wide distribution and occurrence of this species on many seashores worldwide (Nelson, 2006).
Potato tuberworm: impact and methods for control - mini review.
Authors: YuLin Gao
Published: April 2021

The potato tuberworm,
Phthorimaea operculella
Zeller, is one of the most economically significant insect pests of potato in both field and storage worldwide. The biology of the pest and various management strategies such as cultural practices, biological, and chemical control and other control methods are reviewed.
Lumpers and splitters: Birth of Th17 cells
Authors: Stockinger Brigitta
Published: April 2021

Th17 cells were born as a new subset of CD4 T cells to complement Th1, Th2, and T reg cells. From their identification as a distinct subset, they quickly became the paradigm for the astonishing plasticity that CD4 T cells can exhibit depending on tissue environment and circumstances.
DataVault: a data storage infrastructure for the Einstein Toolkit
Authors: Luo Yufeng , Haas Roland , Zhang Qian , Allen Gabrielle
Published: April 2021

Data sharing is essential in the numerical simulations research. We introduce a data repository, DataVault, which is designed for data sharing, search and analysis. A comparative study of existing repositories is performed to analyze features that are critical to a data repository. We describe the architecture, workflow, and deployment of DataVault, and provide three use-case scenarios for different communities to facilitate the use and application of DataVault. Potential features are proposed and we outline the future development for these features.
Electron collisions with molecular nitrogen in its ground and electronically excited states using the R-matrix method
Authors: Su He , Cheng Xinlu , Zhang Hong , Tennyson Jonathan
Published: April 2021

A comprehensive study of electron collisions with the X
1Σg
+ ground state as well as the metastable A
3Σu
+ and a
1Πg excited states of the N2 molecule is reported using the fixed-nucleus R-matrix method. Integral elastic scattering and electronic excitation cross sections from the X
1Σg
+ ground state to the eight lowest electronic states, A
3Σu
+, B
3Πg, W
3Δu, B′
3Σu
−, a
1Πg, a′
1Σu
−, w
1Δu and C
3Πu, overall agree well with the available experimental and theoretical results although updates of some recommended values are suggested. Accurate electron impact electronic transition cross sections starting from the A
3Σu
+ and a
1Πg metastable excited states are reported. The total summed electronic transition cross sections from the a
1Πg state is dominant: an order of magnitude higher than those of the X
1Σg
+ ground state. The de-excitation cross sections generally show a downward trend with increasing incident electron energy, which is different from the elastic and electronic excitation cross sections which generally increase with collision energy. There is a prominent 2Πu symmetry resonance peak at 2.8 eV for electronic de-excitation scattering of a
1Πg → B
3Πg, which significantly contributes to the total summed cross sections from the a
1Πg excited state. The present results provide a new insight which will aid understanding of electron spectra in the atmosphere of the Earth and Titan.
Dynamic evolution of hyperuniformity in a driven dissipative colloidal system
Authors: Nizam Ü Seleme , Makey Ghaith , Barbier Michaël , Kahraman S Süleyman , Demir Esin , Shafigh Ehsan E , Galioglu Sezin , Vahabli Danial , Hüsnügil Sercan , Güneş Muhammed H , Yelesti Efe , Ilday Serim
Published: April 2021

Hyperuniformity is evolving to become a unifying concept that can help classify and characterize equilibrium and nonequilibrium states of matter. Therefore, understanding the extent of hyperuniformity in dissipative systems is critical. Here, we study the dynamic evolution of hyperuniformity in a driven dissipative colloidal system. We experimentally show and numerically verify that the hyperuniformity of a colloidal crystal is robust against various lattice imperfections and environmental perturbations. This robustness even manifests during crystal disassembly as the system switches between strong (class I), logarithmic (class II), weak (class III), and non-hyperuniform states. To aid analyses, we developed a comprehensive computational toolbox, enabling real-time characterization of hyperuniformity in real- and reciprocal-spaces together with the evolution of several order metric features, and measurements showing the effect of external perturbations on the spatiotemporal distribution of the particles. Our findings provide a new framework to understand the basic principles that drive a dissipative system to a hyperuniform state.
Investigation of the magnetic ground state of GaV4S8 using powder neutron diffraction
Authors: Holt S J R , Ritter C , Lees M R , Balakrishnan G
Published: April 2021

The magnetic ground state of polycrystalline Néel skyrmion hosting material GaV4S8 has been investigated using ac susceptibility and powder neutron diffraction. In the absence of an applied magnetic field GaV4S8 undergoes a transition from a paramagnetic to a cycloidal state below 13 K and then to a ferromagnetic-like state below 6 K. With evidence from ac susceptibility and powder neutron diffraction, we have identified the commensurate magnetic structure at 1.5 K, with ordered magnetic moments of 0.23(2) μ
B on the V1 sites and 0.22(1) μ
B on the V2 sites. These moments have ferromagnetic-like alignment but with a 39(8)° canting of the magnetic moments on the V2 sites away from the V4 cluster. In the incommensurate magnetic phase that exists between 6 and 13 K, we provide a thorough and careful analysis of the cycloidal magnetic structure exhibited by this material using powder neutron diffraction.
In-plane ordered quaternary

M4/3′M2/3″AlB2

phases (i-MAB): electronic structure and mechanical properties from first-principles calculations
Authors: Lind Hans , Dahlqvist Martin , Rosen Johanna
Published: April 2021

We have by means of first principles density functional theory calculations studied the mechanical and electronic properties of the so called i-MAB phases, M
4/3′M″2/3AlB2, where M′ = Cr, Mo, W and M″ = Sc, Y. These phases, experimentally verified for Mo4/3Sc2/3AlB2 and Mo4/3Y2/3AlB2, display an atomically laminated structure with in-plane chemical order between the M′ and M″ elements. Structural properties, along with elastic constants and moduli, are predicted for different structural symmetries, including the reported

R

3

̄

m

(#166) space group. We find all considered i-MAB phases to be metallic with a significant peak in the electronic structure at the Fermi level and no significant anisotropy in the electronic band structure. The simulations also indicate that they are rather hard and stiff, in particular the Cr-based ones, with a Young’s modulus E of 325 GPa for M″ = Sc. The Mo-based phases are similar, with E = 299 GPa for M″ = Sc, which is higher than the corresponding laminated carbides (i-MAX phases).
Silicene/ZnI2 van der Waals heterostructure: tunable structural and electronic properties
Authors: Hassan Md. Sakib , Islam Md. Sherajul , Park Jeongwon
Published: April 2021

By utilizing ab initio density functional theory, the structural and electronic properties of novel silicene/ZnI2 heterobilayers (HBLs) were investigated. Constructing HBLs with ZnI2 in different stacking configurations leads to direct bandgap opening of silicene at K point, which ranges from 138.2 to 201.2 meV. By analyzing the projected density of states and charge density distribution, we found that the predicted HBLs conserve the electronic properties of silicene and ZnI2 can serve as a decent substrate. The tunability of electronic properties can be achieved by enforcing biaxial strain and by varying interlayer distance where bandgap can get as low as zero to as high as 318.8 meV and 290.7 meV, respectively depending on the stacking patterns. Maintenance of the remarkable features of silicene, high mobility of charge carriers, and fine-tuning of bandgap pave the way to construct new nanoelectronic devices using these novel silicene/ZnI2 HBLs.
The adaptation and investigation of cone-beam CT reconstruction algorithms for horizontal rotation fixed-gantry scans of rabbits
Authors: Gardner Mark , Dillon Owen , Shieh Chun-Chien , O’Brien Ricky , Debrot Emily , Barber Jeffrey , Ahern Verity , Bennett Peter , Heng Soo-Min , Corde Stéphanie , Jackson Michael , Keall Paul
Published: April 2021

Fixed-gantry radiation therapy has been proposed as a low-cost alternative to the conventional rotating-gantry radiation therapy, that may help meet the rising global treatment demand. Fixed-gantry systems require gravitational motion compensated reconstruction algorithms to produce cone-beam CT (CBCT) images of sufficient quality for image guidance. The aim of this work was to adapt and investigate five CBCT reconstruction algorithms for fixed-gantry CBCT images. The five algorithms investigated were Feldkamp–Davis–Kress (FDK), prior image constrained compressed sensing (PICCS), gravitational motion compensated FDK (GMCFDK), motion compensated PICCS (MCPICCS) (a novel CBCT reconstruction algorithm) and simultaneous motion estimation and iterative reconstruction (SMEIR). Fixed-gantry and rotating-gantry CBCT scans were acquired of 3 rabbits, with the rotating-gantry scans used as a reference. Projections were sorted into rotation bins, based on the angle of rotation of the rabbit during image acquisition. The algorithms were compared using the structural similarity index measure root mean square error, and reconstruction time. Evaluation of the reconstructed volumes showed that, when compared with the reference rotating-gantry volume, the conventional FDK algorithm did not accurately reconstruct fixed-gantry CBCT scans. Whilst the PICCS reconstruction algorithm reduced some motion artefacts, the motion estimation reconstruction methods (GMCFDK, MCPICCS and SMEIR) were able to greatly reduce the effect of motion artefacts on the reconstructed volumes. This finding was verified quantitatively, with GMCFDK, MCPICCS and SMEIR reconstructions having RMSE 17%–19% lower and SSIM 1% higher than a conventional FDK. However, all motion compensated fixed-gantry CBCT reconstructions had a 56%–61% higher RMSE and 1.5% lower SSIM than FDK reconstructions of conventional rotating-gantry CBCT scans. The results show that motion compensation is required to reduce motion artefacts for fixed-gantry CBCT reconstructions. This paper further demonstrates the feasibility of fixed-gantry CBCT scans, and the ability of CBCT reconstruction algorithms to compensate for motion due to horizontal rotation.
Sparse-domain regularized stripe decomposition combined with guided-image filtering for ring artifact removal in propagation-based x-ray phase-contrast CT
Authors: Li Yimin , Zhao Yuqing , Ji Dongjiang , Lv Wenjuan , Xin Xiaohong , Zhao Xinyan , Liu Dayong , Ouyang Zhaoguang , Hu Chunhong
Published: April 2021

Propagation-based x-ray phase-contrast computed tomography (PB-PCCT) images often suffer from severe ring artifacts. Ring artifacts are mainly caused by the nonuniform response of detector elements, and they can degrade image quality and affect the subsequent image processing and quantitative analyses. To remove ring artifacts in PB-PCCT images, a novel method combined sparse-domain regularized stripe decomposition (SDRSD) method with guided image filtering (GIF) was proposed. In this method, polar coordinate transformation was utilized to convert the ring artifacts to stripe artifacts. And then considering the directional and sparse properties of the stripe artifacts and the continuity characteristics of the sample, the SDRSD method was designed to remove stripe artifacts. However, for the SDRSD method, the presence of noise may destroy the edges of the stripe artifacts and lead to incomplete decomposition. Hence, a simple and efficient smoothing technique, namely GIF, was employed to overcome this issue. The simulations and real experiments demonstrated that the proposed method could effectively remove ring artifacts as well as preserve the structures and edges of the samples. In conclusion, the proposed method can serve as an effective tool to remove ring artifacts in PB-PCCT images, and it has high potential for promoting the biomedical and preclinical applications of PB-PCCT.
Deep learning-based photoplethysmography classification for peripheral arterial disease detection: a proof-of-concept study
Authors: Allen John , Liu Haipeng , Iqbal Sadaf , Zheng Dingchang , Stansby Gerard
Published: April 2021

Objective. A proof-of-concept study to assess the potential of a deep learning (DL) based photoplethysmography PPG (‘DLPPG’) classification method to detect peripheral arterial disease (PAD) using toe PPG signals. Approach. PPG spectrogram images derived from our previously published multi-site PPG datasets (214 participants; 31.3% legs with PAD by ankle brachial pressure index (ABPI)) were input into a pretrained 8-layer (five convolutional layers + three fully connected layers) AlexNet as tailored to the 2-class problem with transfer learning to fine tune the convolutional neural network (CNN). k-fold random cross validation (CV) was performed (for k = 5 and k = 10), with each evaluated over k training/validation runs. Overall test sensitivity, specificity, accuracy, and Cohen’s Kappa statistic with 95% confidence interval ranges were calculated and compared, as well as sensitivities in detecting mild-moderate (0.5 ≤ ABPI < 0.9) and major (ABPI < 0.5) levels of PAD. Main results. CV with either k = 5 or 10 folds gave similar diagnostic performances. The overall test sensitivity was 86.6%, specificity 90.2% and accuracy 88.9% (Kappa: 0.76 [0.70–0.82]) (at k = 5). The sensitivity to mild-moderate disease was 83.0% (75.5%–88.9%) and to major disease was 100.0% (90.5%–100.0%). Significance. Substantial agreements have been demonstrated between the DL-based PPG classification technique and the ABPI PAD diagnostic reference. This novel automatic approach, requiring minimal pre-processing of the pulse waveforms before PPG trace classification, could offer significant benefits for the diagnosis of PAD in a variety of clinical settings where low-cost, portable and easy-to-use diagnostics are desirable.
A conformally flat generalized Ricci recurrent spacetime in F(R)-gravity
Authors: De Avik , Loo Tee-How , Solanki Raja , Sahoo P K
Published: April 2021

In the present paper we study a conformally flat generalized Ricci recurrent perfect fluid spacetime with constant Ricci scalar as a solution of modified F(R)-gravity theory. We show that a Robertson-Walker spacetime is generalized Ricci Recurrent if and only if it is Ricci symmetric. The perfect fluid type matter is shown to have EoS ω = −1. Some energy conditions are analyzed with couple of popular toy models of F(R)-gravity, like F(R) = R + α
R

m
where α, m are constants and

F
(
R
)
=
R
+
β
R
ln
R

where β is constant. In harmony with the recent observational studies of accelerated expansion of the Universe, both cases exhibit that the null, weak, and dominant energy conditions fulfill their requirements whereas the strong energy condition is violated.
Rainfall Threshold of Citarum River Flood for Early Warning on Urban Area
Authors: Safarina Ariani Budi , Chairunnisa  , Lestari Novita Dwi , Aprilianingsih Devi , Syahrullah Fathulhuda Muhammad , Sadidah Muthiah
Published: April 2021

Floods in Bandung basin located in the upper Citarum river resulted in huge losses because they occurred in industrial areas and densely populated settlements. Disaster risk reduction can be done with flood early warning in residential areas. The purpose of this study is to determine the rainfall threshold that causes inundation in residential areas in seven districts located on the floodplain of the Citarum river. The method used is the analysis of the rainfall-runoff model to obtain the Citarum river unit hydrograph. Flows in the rivers are assumed to be one-dimensional unsteady flow whereas overflow is assumed to be overland flow. Threshold rainfall is determined based on the deconvolution method, with the drainage coefficient calculated based on the land use map. The results of the study are the capacity discharge and the load discharge of the Citarum river in the seven sub-districts, which the most upstream is the Majalaya sub-district and the downstream is Katapang sub-district. The lowest threshold rainfall has occurred in the sub-district Bojongsoang that is 54.34 mm that produced the flood water level as high as 662 m MSL. and the evacuation time for early warning is 5.5 hours.
Influence of Temperature and Reaction Time on the Performance of Thermal Pyrolysis of Compact Polystyrene Waste
Authors: Palmay P , Nuñez R , Donoso C , Bruno J
Published: April 2021

The purpose of this study is to determine the influence of the temperature and reaction time on the thermal pyrolysis process of compact polystyrene residues based on the percentage of liquid obtained at a heating cup of 15 C min-1 and cooling system for the condensation of pyrolytic gases at 10 ° C. It worked with temperatures between 375 and 425 °C and times of 5 and 10 minutes. The results showed that the reaction time has no representative influence on the liquid fraction, while the temperature has a great importance in the liquid yield reaching a maximum contribution at 400 °C, after this the percentage of liquid oils tends to decrease by guiding the formation of the gas fraction. The maximum production was 81.4% with a kinematic viscosity of 1,026 mm2 s-1, relative density 0.9352, flash point 24 °C and a caloric power of 48.5 MJ kg-1. The mixture of aromatic hydrocarbons obtained, with carbon chains between C6 and C20, are present in 75% by mass.
National trends in prescription drug expenditures and projections for 2021
Authors: Tichy Eric M , Hoffman James M , Suda Katie J , Rim Matthew H , Tadrous Mina , Cuellar Sandra , Clark John S , Wiest Michelle D , Matusiak Linda M , Schumock Glen T
Published: April 2021

Purpose

To report historical patterns of pharmaceutical expenditures, to identify factors that may influence future spending, and to predict growth in drug spending in 2021 in the United States, with a focus on the nonfederal hospital and clinic sectors.

Methods

Historical patterns were assessed by examining data on drug purchases from manufacturers using the IQVIA National Sales Perspectives database. Factors that may influence drug spending in hospitals and clinics in 2021 were reviewed—including new drug approvals, patent expirations, and potential new policies or legislation. Focused analyses were conducted for biosimilars, cancer drugs, generics, coronavirus disease 2019 (COVID-19) pandemic influence, and specialty drugs. For nonfederal hospitals, clinics, and overall (all sectors), estimates of growth of pharmaceutical expenditures in 2021 were based on a combination of quantitative analyses and expert opinion.

Results

In 2020, overall pharmaceutical expenditures in the United States grew 4.9% compared to 2019, for a total of $535.3 billion. Utilization (a 2.9% increase) and new drugs (a 1.8% increase) drove this increase, with price changes having minimal influence (a 0.3% increase). Adalimumab was the top drug in 2020, followed by apixaban and insulin glargine. Drug expenditures were $35.3 billion (a 4.6% decrease) and $98.4 billion (an 8.1% increase) in nonfederal hospitals and clinics, respectively. In clinics, growth was driven by new products and increased utilization, whereas in hospitals the decrease in expenditures was driven by reduced utilization. Several new drugs that will influence spending are expected to be approved in 2021. Specialty and cancer drugs will continue to drive expenditures along with the evolution of the COVID-19 pandemic.

Conclusion

For 2021, we expect overall prescription drug spending to rise by 4% to 6%, whereas in clinics and hospitals we anticipate increases of 7% to 9% and 3% to 5%, respectively, compared to 2020. These national estimates of future pharmaceutical expenditure growth may not be representative of any particular health system because of the myriad of local factors that influence actual spending.
High level of conservation and diversity among the endophytic seed bacteriome in eight alpine grassland species growing at the Qinghai Tibetan Plateau
Authors: Liang Danni , Guo Jianxiu , Hou Fujiang , Bowatte Saman
Published: April 2021

Seed borne microorganisms play an important role in plant biology. Concerns have recently been raised about loss of seed microbial diversity by seed treatments, crop domestication and plant breeding. Information on the seed microbiomes of native plants growing in natural ecosystems is beneficial as they provide the best settings to detect indigenous plant microbe interactions. Here, we characterized the seed bacterial community of 8 native alpine grassland plants. First, seed bacterial diversity was examined using Illumina DNA sequencing, then 28 cultivable bacteria were isolated and potential functions were explored. Across 8 plant species, 343 different bacterial genera were identified as seed endophytes, 31 of those were found in all plant species, indicating a high level of conservation. Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes and Chloroflexi were the top five dominant phyla. Plant species identity was a key determinant shaping the seed endophytic bacteriome. ACC deaminase activity, siderophores production and secretion of lytic enzymes were common functions shown by isolated bacteria. Our results demonstrate that highly diverse and beneficial bacterial populations are hosted by seeds of alpine grassland species to ensure the establishment of best bacterial symbionts for the next generation. This information is useful for crop improvement by reinstating beneficial seed microbial diversities for high-quality forage and crop seeds.
MONOSOMIC ANALYSIS OF FATTY ACID COMPOSITION IN EMBRYO LIPIDS OF ZEA MAYS L
Authors: Plewa Michael J , Weber David F
Published: April 2021

The effects of monosomy of specific chromosomes on the fatty acid composition of maize embryos were studied. A novel technique was developed to obtain fatty acid profiles of single embryos without reducing the viability of the sampled kernels. Monosomic 2 embryos had significantly more oleic acid and significantly less linoleic acid than diploid control embryos. Since the conversion of oleic acid to linoleic acid is a single-enzyme-mediated reaction, we suggest that a gene involved in linoleic acid biosynthesis is located on chromosome 2. Additional consistent variations were found in other monosomic types. This study demonstrates that monosomic analysis can be used to study gene dosage effects at the biochemical level.
GENETIC CONTROL OF QUERCETIN FORMATION IN THE ALEURONE TISSUE OF MAIZE
Authors: Reddy A R , Reddy G M
Published: April 2021

The genes C, C2, R, A, A2, Bz, Bz2 and Pr are required for the formation of purple anthocyanin in the aleurone tissue of maize, and the recessive gene(s) result in non-purple (red, bronze and colorless). Aleurone extracts of recessive a and certain double recessive combinations were analyzed by paper chromatography, absorption spectra in the ultraviolet (UV) and infrared, mass spectra, and other analytical techniques. Homozygous recessive a tissue accumulates the flavonol, quercetin, while the double combinations a c and a r lack it, suggesting that dominant genes C and R are required for its formation and act prior to A in the synthesis of flavonols, as in the gene action sequence for anthocyanin synthesis. Dominant C-I inhibits the formation of quercetin, whereas Bz, Bz2 and In do not affect its formation. These results suggest a close biogenetic relationship between quercetin and cyanidin-3-glucoside and also independently confirm the position of A in both sequences.
THE GENE ACTION AND FUNCTION OF TWO DOPA OXIDASE POSITIVE MELANOCYTE MUTANTS OF THE FOWL
Authors: Brumbaugh J A , Lee K W
Published: April 2021

Ultrastructural and autoradiographic analysis revealed the developmental genetic differences between the dopa oxidase positive pk and I mutations of the fowl. The differences were revealed by the results of five measurements involving homozygous mutant melanocytes, heterozygous melanocytes, and standard melanocytes at each of the loci. The measurements were: ultrastructural comparisons of melanosomes in pigmented epithelial (PE) and neural crest derived (NC) melanocytes, the number of 3H-dopa and 3H-leucine grains/µ2 of melanosome, the 3H-dopa/3H-leucine ratio, and the percentage of cytoplasmic 3H-leucine grains that were melanosomal. The pk mutation altered both PE and NC melanosomes. +/pk melanocytes were characterized by suppressed 3H-dopa/µ2 and 3H-dopa/3H-leucine values. +/pk cells, however, had the same percentage of melanosomal 3H-leucine grains as the "pk" standard. The I mutation altered only NC melanosomes. +/I melanocytes were characterized by 3H-dopa/µ2 and 3H-dopa/3H-leucine values similar to the "I" standard. +/I cells had a lower percentage of melanosomal 3H-leucine grains than the "I" standard, however. These data suggest that pk is a structural mutation affecting melanin binding to the premelanosome, while I seems to be a control gene mutation partially suppressing the production of premelanosomal components in NC melanocytes.
GENETIC ANALYSIS OF THE 5S RNA GENES IN DROSOPHILA MELANOGASTER
Authors: Procunier James D , Tartof Kenneth D
Published: April 2021

The 5S RNA genes of Drosophila melanogaster in either an isogenic wild-type or a multiply inverted (SM1) chromosome 2 increase their multiplicity when opposite a deficiency for the 5S gene site. This is analogous to the compensation phenomenon previously described for the 18S and 28S ribosomal RNA genes of the X chromosome nucleolus organizer region. Molecular hybridization of 5S RNA to DNA containing various doses of the 56F1-9 region of chromosome 2 demonstrates that most, if not all, of the 5S genes reside in or near this region. Also, a deficiency missing approximately one-half of the wild-type number of 5S genes was isolated and genetically localized. This mutant has a phenotype like that of bobbed, a mutant known to be partially deficient in 18S and 28S ribosomal RNA genes. Finally, we report the existence of a chromosomal rearrangement which splits the second chromosome into two segments, each containing 5S DNA.
ADAPTIVE SIGNIFICANCE OF VEGETATIVE INCOMPATIBILITY IN NEUROSPORA CRASSA
Authors: Hartl Daniel L , Dempster Everett R , Brown Spencer W
Published: April 2021

Certain features reminiscent of sexuality occur in the vegetative life cycle of some filamentous fungi such as Neurospora crassa. Hyphal fusions can occur between genetically different individuals, thereby endowing the new composite mycelium, a heterokaryon, with some of the advantages of heterozygosity usually associated with diploid organisms. In N. crassa, however, there are a number of incompatibility loci which prevent formation of heterokaryons unless the alleles at the incompatibility loci are identical in the two mycelia. The selection pressures that maintain incompatibility polymorphisms are not known. We suggest here that they are maintained because they prevent a kind of exploitation of heterokaryons by nuclei that are nonadaptive in homokaryons but that enjoy a proliferative advantage over other nuclei in heterokaryons. A mathematical model that abstracts the major features of the vegetative life cycle of Neurosopra crassa has been developed, and the action of selection in this model and various extensions of it is such as to maintain polymorphisms of vegetative incompatibility factors.
FURTHER STUDIES ON THE BALANCE BETWEEN Adh1 AND Adh2 IN MAIZE: GENE COMPETITIVE PROGRAMS
Authors: Freeling Michael
Published: April 2021

Two unlinked genes which specify alcohol dehydrogenase (ADH) enzymes in maize are coordinately regulated by competition for a factor which limits the rate of total ADH expression during anaerobiosis. The "gene competition hypothesis" and the existence of organ-specific competitive programs, as proposed by Schwartz (1971), is further supported. The potential balance of expression between these two genes appears to be organ-specific and may be "locked-in" and inherited via meristematic growth. The actual expression of these two genes is dependent on the mode of ADH induction. The discussion examines alternative hypotheses explaining gene competition and reinterprets extant data on the adaptive significance of maize ADH polymorphism.
THE SYNTHESIS OF 5S RNA AND ITS RELATIONSHIP TO 18S AND 28S RIBOSOMAL RNA IN THE BOBBED MUTANTS OF DROSOPHILA MELANOGASTER
Authors: Mohan Jag
Published: April 2021

Ribosomes contain one molecule each of 5S, 18S and 28S RNA. In Drosophila melanogaster although the genes for 18S+28S are physically separated from the 5S RNA genes, the multiplicity of various ribosomal RNA genes is roughly the same. Thus a coordinate synthesis of these three molecules might seem feasible. This problem has been approached by determining the molar ratios of various RNA's in ovaries and in adult flies. In ovaries there is a slight excess of 5S RNA molecules over other rRNA's, but in adult flies no such differences exist. Bobbed mutants also have the same molar ratios as wild-type flies. Results on 5S RNA synthesis in both in vitro and in vivo studies show that it is reduced in coordination with 18S+28S rRNA in the bobbed mutants of Drosophila melanogaster. Various possibilities are discussed in considering the implications of these results.
CYTOPLASMIC STERILITY FACTORS IN VICIA FABA L
Authors: Edwardson J R , Bond D A , Christie R G
Published: April 2021

Tissues of cytoplasmic male sterile, maintainer, restorer, and restored lines, and sterile plants which reverted to fertility in Vicia faba were examined in ultrathin sections. Cytoplasmic spherical bodies (CSB), ca. 70 nm in diameter, were observed in tissues of all sterile plants but not in tissues of maintainer, restorer or restored sterile plants. No CSB were observed in a reverted fertile branch of a tiller-sterile plant, nor in 5 of 6 reverted fertile plants. One reverted fertile plant contained CSB in ovules. It is proposed that the CSB are the sites of, or possibly, products of, sterility factors in Vicia faba.
GENETIC ANALYSIS OF PETITE MUTANTS OF SACCHAROMYCES CEREVISIAE: TRANSMISSIONAL TYPES
Authors: Perlman Philip S
Published: April 2021

We have studied a number of petite [rho  -] mutants of Saccharomyces cerevisiae induced in a wild-type strain of mitochondrial genotype [ome  -  CHLR ERYS OLIS  1,2,3 PARS] by Berenil and ethidium bromide, all of which have retained two mitochondrial genetic markers, [CHLR] and [ERYS], but have lost all other known markers. Though stable in their ability to retain these markers in their genome, these mutants vary widely among themselves in suppressiveness and in the extent to which the markers are transmitted on crossing to a common wild-type tested strain. In appropriate crosses all of the strains examined in this study demonstrate mitochondrial polarity, and thus have also retained the [ome  -] locus in a functional form; however, five different transmissional types were obtained, several of them quite unusual, particularly among the strains originally induced by Berenil. One of the most interesting types is the one that appears to reverse the parental genotypes with [CHLR ERYS] predominating over [CHLS ERYR] in the diploid [rho+] progeny, rather than the reverse, which is characteristic of analogous crosses with [rho+] or other petites. Mutants in this class also exhibited low or no suppressiveness. Since all of the petites reported here are derived from the same wild-type parent, and so have the same nuclear background, we have interpreted the transmissional differences as being due to different intramolecular arrangements of largely common retained sequences.
SELECTION OF EXTRANUCLEAR MUTANTS OF NEUROSPORA CRASSA
Authors: Rosenberg Emiko , Mora Christina , Edwards David L
Published: April 2021

A procedure is described that produces primarily extranuclear mutants of Neurospora crassa. An analysis of five mutants, [cni-3], [cni-4], [rsp-2], [rsp-3], [rsp-4] is presented. All five mutants segregate in an extranuclear manner. They can be assorted into two classes based on their respiratory properties: (1) those with cyanide-insensitive respiration (cni); (2) those with slow respiration (rsp). All of the mutants are female sterile. The respiratory trait can be placed in different nuclear backgrounds by heterokaryotic transfer. The abnormal respiratory traits are observed in mitochondria isolated from the mutants and it is likely that the mutations are in mitochondrial DNA.
FURTHER STUDIES ON THE RIBOSOMAL RNA CISTRONS OF SCIARA COPROPHILA (DIPTERA)
Authors: Gerbi Susan A , Crouse Helen V
Published: April 2021

Additional experiments with homologous as well as heterologous hybridization confirmed our previous finding in Sciara coprophila that XX females have nearly twice the number of ribosomal RNA cistrons as X0 males. A comparison between two different X' chromosomes revealed that only the one carrying the irradiation-induced Wavy mutation has a deletion of 70% of its ribosomal RNA cistrons as compared to the standard X. The deletion is relatively stable, and the remaining ribosomal RNA cistrons do not appear to undergo disproportionate replication or magnification as in Drosophila. Homologous hybridization experiments revealed an unusually low reiteration of ribosomal RNA cistrons in this fly, 45 gene copies per X chromosome. The question is raised as to whether such a low number of cistrons may be related to the unusual nucleolar condition encountered in the Sciaridae.
THE CYTOGENETIC STUDY OF CROSSING OVER IN INTERSPECIFIC HYBRIDS BETWEEN DROSOPHILA VIRILIS AND D. TEXANA
Authors: Evgen'ev M B
Published: April 2021

Spontaneous crossing over was studied by means of combined cytological and genetic methods in F1  Drosophila virilis x D. texanafemales (series I) and in D. virilis females carrying a D. texana fifth chromosome in heterozygous condition (series II). The main criterion utilized to distinguish the oogonial crossovers from the meiotic ones is the identity of cytological positions of genetic exchange in crossovers constituting a cluster. Five clusters of crossovers with identical positions of exchange were found in the first series of experiments. In the second series of experiments not a single cluster of crossovers resulting from oogonial crossing over was found.
MEIOSIS IN MALE DROSOPHILA MELANOGASTER. II. NONRANDOM SEGREGATION OF COMPOUND-SECOND CHROMOSOMES
Authors: Gethmann Richard C
Published: April 2021

The segregation of compound-second chromosomes in males from two different stocks has been examined. Segregation is random in males from the C(2L)RM4, dp; C(2R)RM4, px stock. Gametes containing only one of the two compound chromosomes comprise 50% of the gametes, and gametes containing either both elements or neither element make up the other 50% of the gametes.——In males from the C(2L)RM, b; C(2R)RM, cn stock, gametes containing either C(2L)RM, b or C(2R)RM, cn make up the majority of the gametes. Gametes containing both chromosomes or neither chromosome account for only 2-3% of the gametes. The nonrandom segregation is due to the C(2R)RM, cn chromosome.——Viability is reduced in flies carrying the C(2R)RM, cn chromosome. This includes larval lethality, delayed development and premature adult lethality. Cytologically, this chromosome contains a large duplication of 2L material, which includes material proximal to region 38 or 39. It is suggested that the viability and segregational properties associated with this chromosome are due to the duplicated 2L material.
GENETIC ANALYSIS OF ASPARTATE AMINOTRANSFERASE ISOZYMES FROM HYBRIDS BETWEEN DROSOPHILA MELANOGASTER AND DROSOPHILA SIMULANS AND MUTAGEN-INDUCED ISOZYME VARIANTS
Authors: Grell E H
Published: April 2021

The aspartate aminotransferases (designated GOT1 and GOT2) are two enzymes of Drosophila melanogaster for which naturally occurring electrophoretic variants were not found. There is an electrophoretic difference between D. melanogaster and D. simulans. Since the F1 hybrid offspring of these species are sterile, a genetic analysis of the ordinary type cannot be done on differences between the two species. A method was devised to make "partial hybrids" in which one chromosome arm is homozygous for melanogaster genes in an otherwise hybrid background. By using this method, Got1 was localized to 2R and Got2 to 2L. Once a gene can be assigned to a chromosome, it may be followed in crossing schemes and mutations from mutagen treatments may be looked for. At the locus of Got1 a mutation with low activity was recovered and designated Got1lo. It was located at a genetic map position of 75 on 2R. A Got2 mutant with a greater migration to the anode was recovered and designated Got2J. It was located at a genetic map position of 3.0, and in the salivary chromosome was between 22B1 and 22B4 inclusive.
DIPLOID GYNOGENESIS IN THE MEXICAN AXOLOTL
Authors: Trottier Thomas M , Armstrong John B
Published: April 2021

Gynogenetic diploid axolotls were produced by activating eggs with ultraviolet-inactivated sperm, and then subjecting the activated eggs to heat shock. Optimal conditions for ultraviolet inactivation of the sperm, and for suppression of the second meiotic division by heat shock, were established. Gynogenetic diploids produced by these procedures included progeny homozygous for recessive alleles carried by a heterozygous mother. Gynogenesis could, therefore, be used to uncover new mutations more rapidly than by conventional inbreeding techniques. However, some difficulty was encountered in recognizing mutant phenotypes because of the high incidence of abnormalities and deaths. Defective embryos probably resulted from a combination of heat-shock-induced damage to the eggs and the expression of deleterious recessive alleles carried by the mother.
THE EVOLUTIONARY ADVANTAGE OF RECOMBINATION. II. INDIVIDUAL SELECTION FOR RECOMBINATION
Authors: Felsenstein Joseph , Yokoyama Shozo
Published: April 2021

Based on the Fisher-Muller theory of the evolution of recombination, an argument can be constructed predicting that a recessive allele favoring recombination will be favored, if there are either favorable or deleterious mutants occurring at other loci. In this case there is no clear distinction between individual and group selection. Computer simulation of populations segregating for recessive or dominant recombination alleles showed selection favoring recombination, except in the case of a dominant recombination allele with deleterious background mutants. The relationship of this work to parallel investigations by Williams and by Strobeck, Maynard Smith, and Charlesworth is explored. All seem to rely on the same phenomenon. There seems no reason to assume that the evolution of recombination must have occurred by group selection.
THE GENETICS OF DOPA DECARBOXYLASE IN DROSOPHILA MELANOGASTER. II. ISOLATION AND CHARACTERIZATION OF DOPA-DECARBOXYLASE-DEFICIENT MUTANTS AND THEIR RELATIONSHIP TO THE α-METHYL-DOPA-HYPERSENSITIVE MUTANTS
Authors: Wright Theodore R F , Bewley Glenn C , Sherald Allen F
Published: April 2021

Of 84 lethals isolated over the dopa decarboxylase (DDC) deficiency Df(2L)50, 8 have been identified as DDC-deficient alleles on the basis of their effect on DDC activity when heterozygous over the CyO balancer chromosome with activities ranging from 28% to 53% of controls. Some of the Ddc-deficient alleles exhibit intracistronic complementation. Most of the complementing pairs of alleles are much reduced in viability, e.g. < 5% of expected, and express a common syndrome of mutant phenes which can reasonably be inferred to derive from inadequately sclerotinized cuticle. Individuals heterozygous for the noncomplementing allele, Ddcn7, over the 12-band DDC deficiency, Df(2L)130, die at the end of embryogenesis as unhatched larvae with unpigmented mouth parts.

The Ddc alleles and the l(2)amd α-methyl dopa (αMD) hypersensitive alleles are both located within the 11 band region 37B10-C7. The l(2)amd locus is immediately to the right of hk(2-53.9).Ddc has been mapped within 0.004 Map Units to the right of l(2)amd with a maximum estimated recombination frequency of 0.01%. None of the Ddc/CyO strains are sensitive to the dietary administration of α-methyl dopa (αMD), and complementation occurs between the Ddc deficient alleles and the l(2)amd alleles both on the basis of viability and DDC activity. No effect on DDC by the amd alleles has been found to date. Even in the complementing heterozygote, amdH1/amdH89, the level of activity, thermostability, and in vitro αMD inhibition of DDC remains unaffected. Although no biochemical phene has yet been established for the αMD hypersensitive amd alleles, it seems likely that the two groups of mutants are functionally related.