bluuebunny/crossref_metadata_2025 huggingface dataset:
Competitiveness of the Slovak Republic as a Determinant of its Success in Third Country Markets
Authors: Zábojník Stanislav , Borovská Zuzana
Published: January 2021

Research background: Despite long-term goals of the economic strategy of the Slovak Republic, the Slovak competitiveness on the third countries´ markets is relatively weak considering the long tradition in the export activities of the Czechoslovak companies in the past. In terms of the international trade orientation, we note that the method of the Slovak economic strategy is mainly the pro-export support and placement of the Slovak production on foreign markets. Given the openness of the Slovak economy, competitiveness within these markets is crucial and proves the relevance of the research. Slovak Strategy of the External Economic Relations defines two groups of the priority territories for the support and subsidizing of the Slovak exports.

Purpose of the article: The paper assesses the results of the strategy supporting the Slovak companies on the third markets and an aim of the paper is to define the key indicators of the competitiveness of the Slovak Republic on the third markets of the prioritized territories.

Methods: Authors use basic indicators (export volumes, market share, RCA) as well as export gap method.

Findings & Value added: The study indicates only a very small progress in the catching-up process of the Slovak companies in case of export competitiveness in the preferential territories outside of the EU. A comprehensive comparison of the V4 countries was realized and recommendations for a new strategy were formulated.
Zweitlinientherapie eines Basalzellkarzinoms mittels photodynamischer Therapie als grober Behandlungsfehler
Authors: Elsner P.
Published: January 2021

Ein Hautarzt führte bei einem Patienten 2 Sitzungen einer photodynamischen Therapie zur Behandlung eines Basalzellkarzinoms an der rechten Wange durch. 3 Jahre später wurde der Kläger wegen des Verdachts eines Rezidivs an der rechten Wange ambulant operiert; es waren Nachoperationen erforderlich. Der Patient machte zivilgerichtlich Schadensersatz sowie ein Schmerzensgeld mit der Begründung geltend, er sei nicht über Behandlungsalternativen zur photodynamischen Therapie aufgeklärt worden und diese Therapie habe nicht dem fachmedizinischen Standard entsprochen. Während das zuständige Landgericht seine Klage ablehnend beschied, gab das Oberlandesgericht der Berufung statt und hielt fest, dass ein Behandlungsfehler darin liegt, wenn ein Arzt nicht die Therapie der 1. Wahl, den sog. „Golden Standard“, sondern die Therapie der 2. Wahl anwendet. Verlässt der Arzt den „Goldstandard“, ohne den Patienten hierauf hinzuweisen, so handelt er unverständlich und nicht mehr nachvollziehbar und damit grob fehlerhaft, wenn der Patient bereits zur Durchführung der Therapie der 1. Wahl entschlossen war. Dies führte im vorliegenden Fall zur Beweislastumkehr für die Kausalität des vom Patienten beklagten Gesundheitsschadens.
Verbesserung der psychischen Gesundheit und Bindung bei postpartal psychisch erkrankten Frauen – Evaluation einer interaktionszentrierten Therapie in einer Mutter-Kind-Tagesklinik
Authors: Weidner Kerstin , Junge-Hoffmeister Juliane , Coenen Anne , Croy Ilona , Bittner Antje
Published: January 2021

Ziele Frauen mit postpartalen psychischen Störungen zeigen häufig eine verzögerte Bindungsentwicklung zum Kind mit negativen Folgen für die kindliche Entwicklung. In mehreren Ländern wurde nachgewiesen, dass eine spezifische Mutter-Kind-Behandlung positiv auf die mütterliche Psychopathologie und die Bindungsentwicklung wirkt. Daten für den deutschsprachigen Raum sind rar, auch aufgrund der fehlenden Angebote bei unzureichender Finanzierung. Patientinnen einer psychosomatisch-psychotherapeutischen Mutter-Kind-Tagesklinik werden mit dieser Studie charakterisiert und die Behandlung evaluiert.

Methodik 270 Patientinnen wurden bei Aufnahme und Entlassung aus der Tagesklinik befragt. Die Begleitevaluation umfasste die klinischen Haupt- und Nebendiagnosen nach ICD-10, Angaben zur Behandlungsdauer, Medikation, Angaben zum Kind sowie psychometrische Fragebögen zu mütterlicher Psychopathologie sowie zur wahrgenommenen Bindung zum Kind und dem elterlichen Kompetenzerleben.

Ergebnisse 75% der behandelten Frauen wiesen mehr als eine, im Mittel 2,3 psychische Diagnosen auf. Die häufigsten Hauptdiagnosen waren affektive Störungen (38,5%), neurotische, Belastungs-und somatoforme Störungen (30,7%) sowie Persönlichkeits- und Verhaltensstörungen (20,4%). Ca. 56% berichteten Störungen der Mutter-Kind-Bindung. Die durchschnittliche Therapiedauer betrug 32 Behandlungstage. Zwischen Aufnahme und Entlassung zeigte sich eine hochsignifikante Symptomverbesserung mit sehr hoher Effektstärke [F=288,557 (df=1), p<0,001, Eta²=0,549]. Zur Entlassung wiesen 86,6% unserer Patientinnen keine Mutter-Kind-Bindungsstörung mehr auf.

Diskussion Die Ergebnisse weisen auf potentiell hohe therapeutische Effekte der bindungsfokussierten und interaktionszentrierten Behandlung für die seelische Gesundheit der Mutter, ebenso wie die für die Bindungsentwicklung zum Kind hin.

Schlussfolgerung Die gemeinsame Behandlung von Mutter und Kind sollte ein fester und finanzierter Bestandteil des Versorgungssystems sein, um Chronifizierung und negative Entwicklungsfolgen für das Kind zu verhindern.
Late Abdominal Reoperations after Surgery for Necrotizing Enterocolitis and Spontaneous Intestinal Perforation
Authors: Koivusalo Antti , Karila Kristiina , Pakarinen Mikko
Published: January 2021

Introduction The aim of this study was retrospective assessment of late major reoperations after surgery for necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP) in neonates.

Materials and Methods Appropriate ethical consent was obtained. Data collection was by review of hospital records of 165 successive prematures who underwent surgery for NEC (n = 99) or SIP (n = 66) from 1986 to 2019. Outcome measures were late major abdominal surgeries or endoscopies that occurred after the primary surgical treatment, closure of enterostomies, and weaning from parenteral nutrition (PN). We assessed also risk factors for late abdominal surgeries.

Results Hundred and twenty-six (76%) patients (NEC, n = 70, 71% and in SIP, n = 56, 85%) survived. Median follow-up was 13 (interquartile range: 5.9–23) years. Nineteen (15%) patients underwent late abdominal surgery with 0% mortality. Most common was surgery for small bowel obstruction (SBO) in 12(9.5%) patients (NEC, n = 5; 7.0%, SIP, n = 7; 13%, p = 0.36) with 10-year cumulative risk of 8.7 (95% confidence interval [CI]: 3.5–14). Long duration of PN and development of intestinal failure associated cholestasis (IFAC) increased the risk of SBO surgery, relative risk: 1.0–3.2 (95% CI: 1.0–9.1), p = 0.02–0.03. Other surgeries included serial transverse enteroplasty (NEC, n = 2), incisional hernia repair (n = 3), cholecystectomy (n = 1), and ovarian torsion (n = 1). Twenty (29%) NEC and four (7%) SIP patients required endoscopic assessment of postoperative symptoms (p = 0.003).

Conclusion Late abdominal reoperations occurred in 15% of patients with NEC and SIP with nil mortality. SBO was the main indication. Risk of SBO was similar between NEC and SIP. Long PN and IFAC increased the risk of SBO.
Congenital Adhesion Band Presenting as Intestinal Perforation in an Extremely Low Birth Weight Infant
Authors: Guillen Juan , Ramey Stacey , Parimi Prabhu Satya
Published: January 2021

A 231/7-week-old and 560-g-weighing premature male infant was evaluated on day of life 33 for increased frequency of bradycardias, bilious residual, and an increase in abdominal girth. Physical examination was notable for distended and mild tender abdomen. Investigations revealed pneumoperitoneum with dilated bowel loops and a normal acid–base balance. An urgent exploratory laparotomy demonstrated isolated jejunal perforation with an adhesive band extending from the omentum to the base of the mesentery. A segmental jejunal resection followed by an end-to-end anastomosis was performed. The diagnosis of intestinal perforation was inconsistent with focal spontaneous intestinal perforation and necrotizing enterocolitis. Decision to perform exploratory laparotomy led to diagnosis of congenital adhesion band, a rare clinical condition, and the patient had a favorable outcome. This premature infant made an excellent recovery and the upper gastrointestinal (GI) study demonstrated that the anastomotic site was intact. He is currently tolerating advancing enteral feeds.
Identity of the Vietnamese narrative culture: archetypal journeys from folk narratives to fantasy short stories
Authors: Thi Kim Ngan Nguyen , Thi Thu Hang Nguyen , Van Trung Le
Published: January 2021

The journey to another world is an archetype that exists in the forms of marvelous motifs and is also a typical narrative formula with the purpose of creating diverse versions of Vietnamese folk narratives. The archetypal journey was later reborn and expanded in medieval literature as Vietnamese culture, which has become more complex over time. With the aim of discovering the cultural identity of Vietnamese narratives using sociohistorical approaches and discussing the archetype grounded in specific contexts, this research focuses on journey motifs to the upper and lower world in folk narratives in early collections written in Han characters and in related historical and cultural bibliographies. At the same time, by analyzing the fantasy short stories in Excursive Notes on Weird Stories (Truyen ky man luc) by Nguyen Du, this study aims to discover the process of acculturation and creation of materials and motifs from folk narratives, and it discusses how these motifs have been adapted. This research reveals specific messages about the history, culture, era, voice and true identity of the medieval Vietnamese Confucian. Importantly, this study emphasizes the unification of spiritual power between folklore and Taoism and the powerful and influential competition between Taoism and Confucianism in medieval Vietnamese literature. The analysis shows that by recreating the motifs of the folk narratives, writers have built other world journeys to describe the hidden political discourses and religious conflicts in the thoughts of the human mind in the most ideal form.
Texture classification based on image (natural and horizontal) visibility graph constructing methods
Authors: Pei Laifan , Li Zhaohui , Liu Jie
Published: January 2021

Texture classification is widely used in image analysis and some other related fields. In this paper, we designed a texture classification algorithm, named by TCIVG (Texture Classification based on Image Visibility Graph), based on a newly proposed image visibility graph network constructing method by Lacasa et al. By using TCIVG on a Brodatz texture image database, the whole procedure is illustrated. First, each texture image in the image database was transformed to an associated image natural visibility graph network and an image horizontal visibility graph network. Then, the degree distribution measure [P(k)] was extracted as a key characteristic parameter to different classifiers. Numerical experiments show that for artificial texture images, a 100% classification accuracy can be obtained by means of a quadratic discriminant based on natural TCIVG. For natural texture images, 94.80% classification accuracy can be obtained by a linear SVM (Support Vector Machine) based on horizontal TCIVG. Our results are better than that reported in some existing literature studies based on the same image database.
A septin GTPase scaffold of dynein–dynactin motors triggers retrograde lysosome transport
Authors: Kesisova Ilona A. , Robinson Benjamin P. , Spiliotis Elias T.
Published: January 2021

The metabolic and signaling functions of lysosomes depend on their intracellular positioning and trafficking, but the underlying mechanisms are little understood. Here, we have discovered a novel septin GTPase–based mechanism for retrograde lysosome transport. We found that septin 9 (SEPT9) associates with lysosomes, promoting the perinuclear localization of lysosomes in a Rab7-independent manner. SEPT9 targeting to mitochondria and peroxisomes is sufficient to recruit dynein and cause perinuclear clustering. We show that SEPT9 interacts with both dynein and dynactin through its GTPase domain and N-terminal extension, respectively. Strikingly, SEPT9 associates preferentially with the dynein intermediate chain (DIC) in its GDP-bound state, which favors dimerization and assembly into septin multimers. In response to oxidative cell stress induced by arsenite, SEPT9 localization to lysosomes is enhanced, promoting the perinuclear clustering of lysosomes. We posit that septins function as GDP-activated scaffolds for the cooperative assembly of dynein–dynactin, providing an alternative mechanism of retrograde lysosome transport at steady state and during cellular adaptation to stress.
Intraspecific relationships between floral signals and rewards with implications for plant fitness
Authors: Essenberg Carla J
Published: January 2021

Within-species variation in traits such as petal size or colour often provides reliable information to pollinators about the rewards offered to them by flowers. In spite of potential disadvantages of allowing pollinators to discriminate against less-rewarding flowers, examples of informative floral signals are diverse in form and widely distributed across plant taxa, apparently having evolved repeatedly in different lineages. Although hypotheses about the adaptive value of providing reward information have been proposed and tested in a few cases, a unified effort to understand the evolutionary mechanisms favouring informative floral signals has yet to emerge. This review describes the diversity of ways in which floral signals can be linked with floral rewards within plant species and discusses the constraints and selective pressures on floral signal–reward relationships. It focuses particularly on how information about floral rewards can influence pollinator behaviour and how those behavioural changes may, in turn, affect plant fitness, selecting either for providing or withholding reward information. Most of the hypotheses about the evolution of floral signal–reward relationships are, as yet, untested, and the review identifies promising research directions for addressing these considerable gaps in knowledge. The advantages and disadvantages of sharing floral reward information with pollinators likely play an important role in floral trait evolution, and opportunities abound to further our understanding of this neglected aspect of floral signalling.
Endometrial receptivity and embryo implantation in carnivores—commonalities and differences with other mammalian species
Authors: Paulson Erika Elinor , Comizzoli Pierre
Published: January 2021

Endometrial receptivity and embryo implantation processes are a major point of pregnancy failure in many mammalian species, including humans. Although reproductive biology in many carnivore species remains enigmatic, the few that have been studied so far are invaluable comparative models. The goals of this review are to (1) summarize current data on the mechanisms involved in uterine receptivity and embryo implantation in carnivores, including commonalities and differences with other mammalian species and (2) identify research priorities to better understand a key phenomenon in a critical group of mammals. Besides unique reproductive traits in some carnivores (induced vs. spontaneous ovulation in cats, ovulation at the germinal vesicle stage in dogs), preimplantation embryo development is comparable with other orders. However, the timing of implantation varies, especially in species having an embryonic diapause. Mechanisms involved in endometrial receptivity and decidualization still remain to be fully understood, but specific markers have already been identified. Importantly, the use of endogenous hormones to control the ovarian activity may impact endometrial receptivity and subsequent embryo implantation. Next, research efforts should take advantage of advanced technologies to further study embryo implantation in carnivores and to provide more relevant models to reproductive medicine or for the conservation of rare and endangered species.
Distributed inference for the extreme value index
Authors: Chen Liujun , Li Deyuan , Zhou Chen
Published: January 2021

In this paper we investigate a divide-and-conquer algorithm for estimating the extreme value index when data are stored in multiple machines. The oracle property of such an algorithm based on extreme value methods is not guaranteed by the general theory of distributed inference. We propose a distributed Hill estimator and establish its asymptotic theories. We consider various cases where the number of observations involved in each machine can be either homogeneous or heterogeneous, and either fixed or varying according to the total sample size. In each case we provide a sufficient, sometimes also necessary, condition under which the oracle property holds.
Morphological, ecological and geographical evolution of the Neotropical genusNasa(Loasaceae subfamily Loasoideae)
Authors: Acuña-Castillo Rafael , Romoleroux Katya , Luebert Federico , Henning Tilo , Weigend Maximilian
Published: January 2021

The Andean uplift is recognized as one of the most important events shaping the Neotropical biota. Previous phylogenetic reconstructions of Nasa, a mostly tropical Andean genus, have been unable to address its historical biogeography or ancestral character estimations in detail due to insufficient sampling and phylogenetic resolution. The main goal of the present study is to provide an expanded and highly resolved phylogenetic reconstruction of the genus to address these questions. We were able to sequence 87 of the 125 taxa (species and subspecies) of Nasa, for the plastid markers trnL–trnF, matK, trnS–trnG and rps16. Our results show that Nasa falls into four well-supported clades, clade I is sister to the rest of the genus and is composed of Central Andean species. The remaining three clades are more widely distributed, found also in the Amotape-Huancabamba Zone (AHZ) and the northern Andes. Our morphological analyses were able to identify plausible phylogenetic affinities of most Nasa spp. for which molecular data are unavailable, with three of the morphological clusters composed mostly by species of three well-supported clades (Clades II, III and IV). Historical biogeography indicates that Nasa has a history spanning 50 Myr, its early events predating most of the Andean uplift. Nasa appears to have originally occupied mid-elevation, seasonally dry habitats. By the mid-Miocene (c. 15 Mya) expansion into new forest edge and undergrowth habitats took place. This coincides with renewed uplift that increased the complexity of the abiotic conditions in the Andes. The AHZ is retrieved as the most important centre of diversification since the closure of the West Andean Portal and appears to be a cradle of clades of Nasa. Conversely, the central Andes, the most likely area of origin of the genus, house mostly ancient, species-poor clades.
Galleria mellonella larvae exhibit a weight-dependent lethal median dose when infected with methicillin-resistant Staphylococcus aureus
Authors: Hesketh-Best Poppy J , Mouritzen Michelle V , Shandley-Edwards Kayleigh , Billington Richard A , Upton Mathew
Published: January 2021

Galleria mellonella is a recognised model to study antimicrobial efficacy; however, standardisation across the scientific field and investigations of methodological components are needed. Here, we investigate the impact of weight on mortality following infection with Methicillin-resistant Staphylococcus aureus (MRSA). Larvae were separated into six weight groups (180–300 mg at 20 mg intervals) and infected with a range of doses of MRSA to determine the 50% lethal dose (LD50), and the ‘lipid weight’ of larvae post-infection was quantified. A model of LD50 values correlated with weight was developed. The LD50 values, as estimated by our model, were further tested in vivo to prove our model.

We establish a weight-dependent LD50 in larvae against MRSA and demonstrate that G. mellonella is a stable model within 180–260 mg. We present multiple linear models correlating weight with: LD50, lipid weight, and larval length. We demonstrate that the lipid weight is reduced as a result of MRSA infection, identifying a potentially new measure in which to understand the immune response. Finally, we demonstrate that larval length can be a reasonable proxy for weight. Refining the methodologies in which to handle and design experiments involving G. mellonella, we can improve the reliability of this powerful model.
Fine structure genetic and physical map of the phage P22 tail protein gene.
Authors: Berget P B , Chidambaram M
Published: January 2021

Bacteriophage P22 which are incapable of making functional tail protein can be propagated by the addition of purified mature tail protein trimers to either liquid or solidified medium. This unique in vitro complementation condition has allowed us to isolate 74 absolute lethal tail protein mutants of P22 after hydroxylamine mutagenesis. These phage mutants have an absolute requirement for purified P22 tail protein to be present in a soft agar overlay in order to form plaques and do not grow on any nonsense suppressing strains of Salmonella typhimurium. In order to genetically map and physically locate these mutations we have constructed two complementary sets of fine structure deletion mapping strains using a collection of Tn1 insertions in gene 9, the structural gene for the tail protein. Fourteen bacteriophage P22 strains carrying unique Tn1 transposon insertions (Ap phage) in gene 9 have been crossed with Ap phage carrying Tn1 insertions in gene 20. Phage carrying deletions that arose from homologous recombination between the Tn1 elements were isolated as P22 lysogens. The deletion prophage were shown to be missing all genetic information bracketed by the parental Tn1 elements and thus form a set of deletions into gene 9 from the 5' end of the gene. From the frequency of production of these deletion phage the orientation of the Tn1 insertions in gene 9 could be deduced. The genetic end points of the deletions in gene 9 and thus the order of Tn1 insertions were determined by marker rescue experiments using the original Ap phage. The genetic end points of the deletions in gene 20 were determined in similar experiments using nonsense mutations in gene 20. To locate the physical end points of these deletions in gene 9, DNA containing the Tn1 element has been cloned from each of the original Ap phage into plasmids. The precise point of insertion of Tn1 into gene 9 was determined by restriction enzyme mapping and DNA sequencing of the relevant portions of each of these plasmids. In vitro deletion of different 3' gene 9 sequences in the plasmid clones was accomplished through the use of unique restriction endonuclease sites in Tn1. The resulting plasmids form a set of deletions extending into the 3' end of the gene which are complementary compared to the deletion lysogens.(ABSTRACT TRUNCATED AT 400 WORDS)
The MF alpha 1 gene of Saccharomyces cerevisiae: genetic mapping and mutational analysis of promoter elements.
Authors: Flessel M C , Brake A J , Thorner J
Published: January 2021

The activity and cell-type specificity of the promoter of the MF alpha 1 gene of Saccharomyces cerevisiae were examined by measuring expression of an MF alpha 1-SUC2 gene fusion in MATa, MAT alpha, and MATa/MAT alpha cells. A high level of invertase activity was observed only in MAT alpha cells. Weak expression occurred in MATa cells when the hybrid gene was carried on a multicopy plasmid or on a centromere-containing plasmid, but not when the hybrid gene was integrated at the normal MF alpha 1 locus. Analysis of a set of 5'-deletions of the promoter region of the MF alpha 1-SUC2 gene on the multicopy plasmid indicated that sequences from -354 to -274 upstream of the translational start site were required for high level expression in MAT alpha cells. Smaller internal deletions and insertions within the promoter region of the MF alpha 1-SUC2 gene were inserted into the genome at the normal MF alpha 1 locus. These mutations further delineated four promoter domains important for expression: (1) two 26 bp elements (-365 to -340 and -312 to -287) with imperfect dyad symmetry; (2) a 40 bp segment (-264 to -226) that lies about 120 bp upstream of the TATA box; and (3) the TATA box itself (-128 to -122). The transcriptional start sites of the normal MF alpha 1 promoter and of a mutant lacking the TATA box were determined. The MF alpha 1 locus was mapped to the left arm of chromosome XVI, about 22 cM centromere-proximal to the PEP4 gene.
Developmental genetics of loci at the base of the X chromosome of Drosophila melanogaster.
Authors: Perrimon N , Smouse D , Miklos G L
Published: January 2021

We have conducted a genetic and developmental analysis of the 26 contiguous genetic complementation groups within the 19D3-20F2 interval of the base of the X chromosome, a region of 34 polytene bands delimited by the maroon-like and suppressor of forked loci. Within this region there are four loci which cause visible phenotypes but which have little or no effect on zygotic viability (maroon-like, little fly, small optic lobes and sluggish). There are 22 loci which, when mutated, are zygotic lethals and three of these, legless/runt, folded gastrulation and 13E3, have severe effects on embryonic development. In addition, three visible phenotypes have been defined only by overlapping deficiencies (melanized-like, tumorous head, and varied outspread). We have analyzed the lethal phases and maternal requirement of 58 mutations at 22 of the zygotic lethal loci by means of germline clone analysis using the dominant female sterile technique. Additionally, all lethal complementation groups, as well as a specific subset of deficiencies, have been studied histologically for defects in the development of the central and peripheral embryonic nervous systems.
Zygotic lethals with specific maternal effect phenotypes in Drosophila melanogaster. I. Loci on the X chromosome.
Authors: Perrimon N , Engstrom L , Mahowald A P
Published: January 2021

In order to identify all X-linked zygotic lethal loci that exhibit a specific maternal effect on embryonic development, germline clonal analyses of X-linked zygotic lethal mutations have been performed. Two strategies were employed. In Screen A germline clonal analysis of 441 mutations at 211 previously mapped X-linked loci within defined regions was performed. In Screen B germline clonal analysis of 581 larval and pupal mutations distributed throughout the entire length of the X chromosome was performed. These approaches provide an 86% level of saturation for X-linked late zygotic lethals (larval and pupal) with specific maternal effect embryonic lethal phenotypes. The maternal effect phenotypes of these mutations are described.
Single locus (rol) control of extreme resistance to red cell osmotic lysis: intrinsic mode of gene action.
Authors: Schaefer C A , Dewey M J
Published: January 2021

Previous work has indicated that inbred mouse strains C57BL/6 and DBA/2 produce red cells differing in their sensitivity to osmotic lysis and that the trait is under multigene control. A recombinant inbred strain (BXD-31), produced from C57BL/6 and DBA/2, has red cells manifesting resistance to osmotic lysis far greater than that of either progenitor. We demonstrate here that the fragility difference between BXD-31 and DBA/2 is the consequence of allelic variation at a single autosomal locus, termed rol. The resistance allele (rol') is almost completely recessive to the sensitive one (rols). Results of bone marrow chimera analyses indicate that (1) the mode of rol gene action is by a direct influence on the properties of the red cells rather than an indirect influence on their extracellular milieu, and (2) rol does not affect erythrocyte production and turnover. The fragility difference caused by rol variation is likely to involve the erythrocyte membrane or underlying cytoskeleton, since various red cell properties sensitive to ion metabolism differences are unaffected by the gene.
Population studies on an endemic troglobitic beetle: geographical patterns of genetic variation, gene flow and genetic structure compared with morphometric data.
Authors: Crouau-Roy B
Published: January 2021

Highly specialized obligatory cave beetles endemic to the French Pyrenees offer an opportunity to investigate the relative importance of environmental conditions and ecological characteristics on the organization of genetic variability, to describe the genetic structure of populations, and to assess the extent of gene flow between local populations in relation to geologic structure. Twenty-three geographically close populations of the beetle Speonomus hydrophilus occurring both in caves (reduced fluctuations in many abiotic parameters) and under the deepest layer of soil in mountains (more exposed to climatic variations) were studied. Significant genetic differentiation at 17 allozyme loci was found among populations in close proximity, as well as among those from distant parts of range. On a larger scale, genetic differences among populations appear to result from low dispersal rates between populations. The spatial patterning observed suggests that allozyme frequencies are not responding to environmentally controlled selection. Substantial genetic divergence (F(ST) = 0.112) occurred throughout the range, with important variation in levels of genetic variability (H: 0.065-0.184) among populations. A significant level of substructuring has occurred among the populations with four major geographic areas of similarity indicated. The substructuring of the species into regions suggests an influence of paleoclimatic gradient and paleoenvironment on the population's genetic structure. Also, founder effect and reduced gene flow appear to have influenced populations in the southeastern portion of the range.
The genetic architecture of interspecific variation in mimulus.
Authors: Macnair M R , Cumbes Q J
Published: January 2021

The genetic architecture of various floral and morphological differences between Mimulus cupriphilus and Mimulus guttatus is investigated. M. cupriphilus is believed to have speciated from M. guttatus in the recent past. The two parent species, the F(1) and F(2), and two backcrosses were grown and scored for 23 different characters. The analysis of means revealed significant epistasis for a number of the floral characters, particularly those involving the length of parts. Dominance was generally toward M. guttatus, except for the characters related to flowering time. Analysis of the genetic correlations between characters revealed that there were at least four different polygenic genetic systems, governing flowering time, size of flower, number of spots on the corolla, and general size. An analysis of minimum gene number suggested that there were at least 3-7 genes controlling floral size, and a different three controlling floral spot number. Two other characters, corolla lobe shape and stem color, were produced by independent major gene differences. Annuality was also shown to be heritable. The two species appear to utilize the same gene for copper tolerance. The results are discussed in the light of current theories of speciation.
In situ hybridization analysis of chromosomal homologies in Drosophila melanogaster and Drosophila virilis.
Authors: Whiting J H , Pliley M D , Farmer J L , Jeffery D E
Published: January 2021

Twenty-four biotin-labeled recombinant-DNA probes which contained putative unique-sequence Drosophila melanogaster DNA were hybridized to larval salivary-gland chromosomes of D. melanogaster and Drosophila virilis. All probes hybridized to D. melanogaster chromosomes at the expected sites. However, one probe hybridized to at least 16 additional sites, and one hybridized to one additional site. Thirteen probes hybridized strongly to D. virilis chromosomes, four hybridized weakly and infrequently, and seven did not hybridize. Probes representing two multigene families (beta-tubulin and yolk-protein) hybridized as would be expected if all sites had been conserved in the two species on the same chromosomal elements. The multiple hybridization sites of a third probe which may represent a multigene family were also conserved. The results were consistent with H.J. Muller's proposal that chromosomal elements have been conserved during evolution of this genus.
Gustave Malécot and the transition from classical to modern population genetics.
Authors: Nagylaki T
Published: January 2021

The contributions of Gustave Malécot to theoretical population genetics are described, discussed, and put into perspective relative to earlier and later work. In this context, certain aspects of the theory of inbreeding, the correlation between relatives, the evolution of finite panmictic populations, and (in more depth) spatial variation are reviewed. A brief biographical sketch of Malécot is also presented.
Molecular evolution of the telomere-associated MAL loci of Saccharomyces.
Authors: Charron M J , Read E , Haut S R , Michels C A
Published: January 2021

The MAL gene family of Saccharomyces consists of five multigene complexes (MAL1, MAL2, MAL3, MAL4, and MAL6) each of which encodes maltose permease (GENE 1), maltase (GENE 2) and the trans-acting MAL-activator (GENE 3). Four of these loci have been mapped and each is located at or near the telomere of a different chromosome. We compare the physical structure of the MAL loci and their flanking sequences. The MAL loci were shown to be both structurally and functionally homologous throughout an approximately 9.0-kb region. The orientation of the MAL loci was determined to be: CENTROMERE . . . GENE 3-GENE 1-GENE 2 . . . TELOMERE. Telomere-adjacent sequences were found flanking GENE 2 of the MAL1, MAL3 and MAL6 loci. No common repeated elements were found on the centromere-proximal side of all the MAL1, loci. These results suggest that, during the evolution of this polygenic family, the MAL loci translocated to different chromosomes via a mechanism that involved the rearrangement(s) of chromosome termini.
Excision repair of UV radiation-induced DNA damage in Caenorhabditis elegans.
Authors: Hartman P S , Hevelone J , Dwarakanath V , Mitchell D L
Published: January 2021

Radioimmunoassays were used to monitor the removal of antibody-binding sites associated with the two major UV radiation-induced DNA photoproducts [cyclobutane dimers and (6-4) photoproducts]. Unlike with cultured human cells, where (6-4) photoproducts are removed more rapidly than cyclobutane dimers, the kinetics of repair were similar for both lesions. Repair capacity in wild type diminished throughout development. The radioimmunoassays were also employed to confirm the absence of photoreactivation in C. elegans. In addition, three radiation-sensitive mutants (rad-1, rad-2, rad-7) displayed normal repair capacities. An excision defect was much more pronounced in larvae than embryos in the fourth mutant tested (rad-3). This correlates with the hypersensitivity pattern of this mutant and suggests that DNA repair may be developmentally regulated in C. elegans. The mechanism of DNA repair in C. elegans as well as the relationship between the repair of specific photoproducts and UV radiation sensitivity during development are discussed.
Transposition Pattern of the Maize Element Ac from the Bz-M2(ac) Allele.
Authors: Dooner H K , Belachew A
Published: January 2021

The pattern of transposition of Ac from the mutable allele bz-m2(Ac) has been investigated. Stable (bz-s) and finely spotted (bz-m(F)) exceptions were selected from coarsely spotted bz-m2(Ac) ears. The presence or absence of a transposed Ac (trAc) in the genome was determined and, when present, the location of the trAc was mapped relative to the flanking markers sh and wx. The salient general features of Ac transposition to sites linked to bz are that the receptor sites tend to be clustered on either side of the bz donor site and that transposition is bidirectional and nonpolar. Thus, the symmetrical clustering in the distribution of receptor sites adjacent to bz differs from the asymmetrical clustering reported in 1984 for the P locus by I. M. GREENBLATT. Though Ac tends to transpose preferentially to closely linked sites, an appreciable fraction of Ac transpositions from bz-m2(Ac) is to unlinked sites: 41% among bz-s derivatives and 59% among bz-m(F) derivatives. Many transposition events among the bz-m(F) selections result in kernels carrying a genetically noncorresponding embryo. These can be interpreted as twin sectors arising at one of the megagametophytic mitoses. The bz locus data fit the earlier (1962) model of I. M. GREENBLATT and R. A. BRINK in which transposition takes place from a replicated donor site to either an unreplicated or replicated receptor site.
Identification and characterization of a new gene of Escherichia coli K-12 involved in outer membrane permeability.
Authors: Sampson B A , Misra R , Benson S A
Published: January 2021

Using a genetic selection for mutations which allow large maltodextrins to cross the outer membrane of Escherichia coli in the absence of the LamB maltoporin, we have obtained and characterized two mutations that define a new locus of E. coli. We have designated this locus imp for increased membrane permeability. Mapping studies show that the imp gene resides at approximately 1.2 min on the E. coli chromosome. The mutations alter the permeability of the outer membrane resulting in increased sensitivity to detergents, antibiotics and dyes. The mutations are nonreverting and codominant. Genetic analysis of the mutations suggest that the imp gene is an essential gene. We describe a general cloning strategy that can be used to clone both dominant and recessive alleles. Using this technique, we have cloned the wild-type and mutant imp alleles onto a low copy number plasmid.
Genetic and molecular analysis of recombination events in Saccharomyces cerevisiae occurring in the presence of the hyper-recombination mutation hpr1.
Authors: Aguilera A , Klein H L
Published: January 2021

The hyper-recombination mutation hpr1 specifically increases mitotic intrachromatid crossovers, with no effect on other mitotic recombination events such as unequal sister chromatid exchange and plasmid-chromosome recombination, and no effect on meiotic recombination and a lesser effect on intrachromosomal gene conversion. The excision repair RAD1 gene is partially required for the expression on the hpr1 phenotype. The simplest hypothesis to account for some of the hpr1 stimulated recombination events is that a heteroduplex DNA intermediate and localized gene conversion are involved. hpr1 stimulated crossover events are independent of intrachromosomal gene conversion events stimulated by the hyper-gene conversion mutation hpr5. This result suggests that different intrachromosomal recombination processes are affected in each mutant strain. We propose that HPR1 may function to inhibit intrachromatid crossovers.
Genetic and physical analysis of double-strand break repair and recombination in Saccharomyces cerevisiae.
Authors: Rudin N , Sugarman E , Haber J E
Published: January 2021

We have investigated HO endonuclease-induced double-strand break (DSB) recombination and repair in a LACZ duplication plasmid in yeast. A 117-bp MATa fragment, embedded in one copy of LACZ, served as a site for initiation of a DSB when HO endonuclease was expressed. The DSB could be repaired using wild-type sequences located on a second, promoterless, copy of LACZ on the same plasmid. In contrast to normal mating-type switching, crossing-over associated with gene conversion occurred at least 50% of the time. The proportion of conversion events accompanied by exchange was greater when the two copies of LACZ were in direct orientation (80%), than when inverted (50%). In addition, the fraction of plasmids lost was significantly greater in the inverted orientation. The kinetics of appearance of intermediates and final products were also monitored. The repair of the DSB is slow, requiring at least an hour from the detection of the HO-cut fragments to completion of repair. Surprisingly, the appearance of the two reciprocal products of crossing over did not occur with the same kinetics. For example, when the two LACZ sequences were in the direct orientation, the HO-induced formation of a large circular deletion product was not accompanied by the appearance of a small circular reciprocal product. We suggest that these differences may reflect two kinetically separable processes, one involving only one cut end and the other resulting from the concerted participation of both ends of the DSB.
Genetic variability for pathogenicity, isozyme, ribosomal DNA and colony color variants in populations of Rhynchosporium secalis.
Authors: McDermott J M , McDonald B A , Allard R W , Webster R K
Published: January 2021

Samples of Rhynchosporium secalis were collected from two experimental barley populations known to carry a diverse array of alleles for resistance to this fungal pathogen. Classification of 163 isolates for four putative isozyme systems, a colony color dimorphism and 20 ribosomal DNA restriction fragment length variants revealed 49 different multilocus phenotypes (haplotypes). The six most common haplotypes differed significantly in pathogenicity. Genetic analyses of the data indicated that effective population sizes of the fungus were very large, that the effects of genetic drift were small, and that negligible recombination occurred in the populations studied. Frequency dependent selection was suggested as an explanation for the maintenance of variation in pathogenicity in the fungus.
Extragenic suppression and synthetic lethality among Chlamydomonas reinhardtii mutants resistant to anti-microtubule drugs.
Authors: James S W , Silflow C D , Thompson M D , Ranum L P , Lefebvre P A
Published: January 2021

The antimicrotubule agents oryzalin (ORY), colchicine (COL) and taxol (TAX) were used to select three recessive, conditional lethal (ts-) mutants which defined two new essential loci, ory1 and cor1. The two ory1 mutants conferred resistance to ORY, TAX, and COL; the cor1 mutant conferred resistance only to COL. Each of the mutants displayed wild-type sensitivity to a number of unrelated inhibitors. Assembly and disassembly of flagellar microtubules in the ory1 mutants displayed wild-type sensitivity to ORY and COL, suggesting that the ory1 gene product either does not participate in these processes or the ory1 gene product alone is not sufficient to confer resistance. The ory1 locus mapped to linkage group X; cor1 was mapped to the left arm of linkage group XII. A synthetic lethal interaction was observed between ory1 and cor1 mutations, i.e., inferred ory1 cor1 double mutants were inviable at the permissive temperature. The conditional lethal phenotype of ory1-1 was used to select many spontaneous TS+ revertants, which arose at high frequencies. Genetic and phenotypic characterization of the revertants demonstrated that (1) the revertants fell into four phenotypic classes, including some which conferred supersensitivity to ORY and others which conferred cold-sensitive lethality, (2) reversion was caused in most or all cases by extragenic suppressors, (3) suppressor mutations displayed complex behavior in heterozygous (sup/+) diploids, (4) many different loci may be capable of suppressing ory1 mutants, and (5) suppressors of ory1-1 efficiently suppressed an independently isolated allele, ory1-2. Taken together the ory1, cor1, and suppressor mutations identify a number of interacting loci involved in essential cellular processes which are specifically susceptible to antimicrotubule agents.
Reciprocal recombination and the evolution of the ribosomal gene family of Drosophila melanogaster.
Authors: Williams S M , Kennison J A , Robbins L G , Strobeck C
Published: January 2021

The role of reciprocal recombination in the coevolution of the ribosomal RNA gene family on the X and Y chromosomes of Drosophila melanogaster was assessed by determining the frequency and nature of such exchange. In order to detect exchange events within the ribosomal RNA gene family, both flanking markers and restriction fragment length polymorphisms within the tandemly repeated gene family were used. The vast majority of crossovers between flanking markers were within the ribosomal RNA gene region, indicating that this region is a hotspot for heterochromatic recombination. The frequency of crossovers within the ribosomal RNA gene region was approximately 10(-4) in both X/X and X/Y individuals. In conjunction with published X chromosome-specific and Y chromosome-specific sequences and restriction patterns, the data indicate that reciprocal recombination alone cannot be responsible for the observed variation in natural populations.
Molecular and genetic organization of the suppressor of sable and minute (1) 1B region in Drosophila melanogaster.
Authors: Voelker R A , Huang S M , Wisely G B , Sterling J F , Bainbridge S P , Hiraizumi K
Published: January 2021

Recessive mutations at the suppressor of sable [su(s)] locus in Drosophila melanogaster result in suppression of second site mutations caused by insertions of the mobile element 412. In order to determine whether su(s) mutations might have other phenotypes, a saturation mapping of the su(s) region was carried out. The screen yielded 76 mutations that comprise ten genetic complementation groups ordered distal to proximal as follows: l(1)1Bh, l(1)1Bi, M(1)1B, su(s), l(1)1Bk, l(1)1Ca, mul, tw, l(1)lDa and brc. Twenty-three of the mutations are su(s) alleles, and all are suppressors of the 412-insertion-caused v1 allele. Although the screen could have detected su(s) mutations causing sex-specific dominant lethality or sterility as well as all types of recessive lethality or sterility, the only other phenotype observed was male sterility that is enhanced by cold temperature. This type of sterility is exhibited only by alleles induced by base-substitution-causing mutagens. Genetic functions of the poly(A+) messages transcribed from the su(s) microregion were identified by the reintroduction of cloned sequences into embryos by P element transformation. su(s) function has been attributed to a 5-kb message. The segment of DNA encoding only this 5-kb message rescues both the suppression and cold-sensitive male sterility phenotypes of su(s). Minute (1) 1B has been provisionally identified as encoding a 3.5-kb message; lethal (1)1Bi encodes a 1-kb message; and lethal (1)1Bk encodes a 4-kb message. The possible functions of su(s) and M(1)1B are discussed.
Recombinant inbred strain and interspecific backcross analysis of molecular markers flanking the murine agouti coat color locus.
Authors: Siracusa L D , Buchberg A M , Copeland N G , Jenkins N A
Published: January 2021

Recombinant inbred strain and interspecific backcross mice were used to create a molecular genetic linkage map of the distal portion of mouse chromosome 2. The orientation and distance of the Ada, Emv-13, Emv-15, Hck-1, Il-1a, Pck-1, Psp, Src-1 and Svp-1 loci from the beta 2-microglobulin locus and the agouti locus were established. Our mapping results have provided the identification of molecular markers both proximal and distal to the agouti locus. The recombinants obtained provide valuable resources for determining the direction of chromosome walking experiments designed to clone sequences at the agouti locus. Comparisons between the mouse and human genome maps suggest that the human homolog of the agouti locus resides on human chromosome 20q. Three loci not present on mouse chromosome 2 were also identified and were provisionally named Psp-2, Hck-2 and Hck-3. The Psp-2 locus maps to mouse chromosome 14. The Hck-2 locus maps near the centromere of mouse chromosome 4 and may identify the Lyn locus. The Hck-3 locus maps near the distal end of mouse chromosome 4 and may identify the Lck locus.