bluuebunny/crossref_metadata_2025 huggingface dataset:
Vermittlung des biopsychosozialen Modells in der universitären Lehre: Konzeption und Durchführung eines Seminars mit Betroffenen und Experten aus Dermatologie und Psychosomatik
Authors: Spreckelsen R. , Wittbecker L. , Gerdes S. , Mrowietz U. , Emmert H. , Gläser R.
Published: January 2021

Ziel der Studie Zahlreiche Studien zeigen, dass chronisch entzündliche Hauterkrankungen mit starken Einbußen in nahezu allen Dimensionen der gesundheitsbezogenen Lebensqualität einhergehen. Ziel war es daher, in der universitären dermatologischen Lehre ein extracurriculares Seminar anzubieten, um Medizinstudierenden bereits während ihrer Ausbildung praxisnah das erweiterte biopsychosoziale Modell zu vermitteln und sie frühzeitig für das psychosomatische Grundverständnis zu sensibilisieren.

Methodik Den Studierenden der Dermatologie (i. a. 7. Semester) wurde seit dem Wintersemester 2018/2019 ein zusätzliches Format auf freiwilliger Basis als einmaliges Seminar angeboten, durchgeführt und evaluiert. Insgesamt nahmen 25 Studierende teil, und 22 Fragebögen wurden anschließend deskriptiv und inhaltsanalytisch ausgewertet.

Ergebnisse Die Ergebnisse zeigen, dass großes Interesse und Offenheit für das psychosomatische Grundverständnis seitens der Studierenden besteht. Dabei wurde deutlich, dass die konkrete Option auf ein gemeinsames Zusammentreffen von interessierten Studierenden, Betroffenen und Fachärzten aus Dermatologie und Psychosomatik eine besondere Rolle einnimmt. Studierende nehmen die übliche Fokussierung auf das rein Biologische als unipolar und unvollständig in ihrer derzeitigen universitären Ausbildung wahr.

Schlussfolgerung Fächerübergreifende Seminare unter Anwesenheit von Betroffenen und im gemeinsamen fächerübergreifenden Diskurs tragen zur frühzeitigen Sensibilisierung auf das gleichzeitige Vorliegen von psychologischen und physiologischen Prozessen innerhalb ein und desselben Ereignisvorgangs bei. Die holistische Betrachtung scheint einen günstigen Einfluss für die eigene innere Haltung eines zukünftigen Arztes oder einer zukünftigen Ärztin zu haben.
Quality evaluation of breast meat from chickens fed cassava leaf meal-based diets
Authors: Bakare Archibold G. , Cawaki Panapasa , Ledua Ilaitia , Bautista-Jimenez Vingelle , Kour Gurdeep , Sharma Ami C. , Tamani Eroni
Published: January 2021

Context
Feed supply is an important constraint for poultry production in South Pacific island nations. The use of non-conventional feed resources, such as cassava leaves, could partly fill the gap in the feed supply and reduce feed production costs. Cassava leaves are locally available in South Pacific island nations, but the effects of including these in the diet of chickens are not known.

Aim
It was hypothesised that cassava leaf meal (CLM) at levels of 0%, 10%, 20% and 30% in diets of broiler chickens did not affect the chemical and sensory attributes of breast meat.

Methods
A total of 80 Cobb 500 female broilers were fed treatment diets with CLM included at levels of 0%, 10%, 20% and 30% DM from the age of 21 days to 49 days. Twenty chickens were subjected to each treatment diet. Samples of pectoralis major muscles (breast meat) from chickens fed the treatment diets were removed and analysed for chemical and sensory parameters.

Key results
Ash, crude fat and carbohydrate content were low in breast meat of chickens fed diets with higher inclusion levels of CLM (30%) compared with breast meat of chickens fed other treatment diets (P < 0.05). There was a quadratic relationship between ash content of breast meat and inclusion levels of CLM in the diets of chickens (P < 0.05). No relationships were observed between sensory attributes of breast meat and inclusion levels of CLM in the diets of chickens. Principal component analysis showed the first four principal components (PC) with an eigenvalue >1 account for 77.1% of the total variance for quality parameters of breast meat from chicken fed CLM-based diets. The two main components (PC1 vs PC2) together explained 52.46% of the variation. The data on panellists generated by PC1 versus PC2 plot suggests that the roasted breast meat could be separated by different treatment groups.

Conclusion
The results show that CLM inclusion in the diets of chickens does not affect the sensory qualities of chicken breast meat. Chemical attributes of breast meat were, however, affected when broiler chickens were fed CLM-based diets

Implication
Further exploration of the fatty acid profile and oxidative stability of breast meat from chickens fed CLM-based diets is essential for human clinical application and the meat processing industry.
Abiotic factors in horticultural crops.
Authors: Morgan Lynette
Published: January 2021

Abiotic disorders in horticultural crops are those caused by non-living or non-infectious factors, which may also be referred to as abiotic disease or physiological disorders. Abiotic factors refer to a wide range of plant and crop problems with varied symptoms and differing degrees of damage. Abiotic disorders are often associated with causal factors such as temperature/weather, soils, water, chemicals, mechanical injuries, cultural practices and, in some cases, a genetic predisposition within the plant itself (Schutzki and Cregg, 2007). It has been suggested that the environmental abiotic factors alone can limit crop production by as much as 70% (Boyer, 1982). The yields of major food crops are expected to decline in many areas in the future due to the continued reduction in arable land, reduction of water resources, increased global warming and climate change (Lobell et al., 2011). An FAO report published in 2007 stated that 96.5% of global rural land area is affected in some way by abiotic stress (van Velthuizen et al., 2007), with factors such as temperature, mineral deficiency, drought, flooding and salinity being the most significant issues. While abiotic factors that have a negative effect on plant growth primarily reduce yields and productivity, they also influence produce quality, postharvest shelf life, susceptibility to pathogens, and marketability of a wide range of food and ornamental plants. There is also a complex relationship between many abiotic factors with light, temperature, moisture and nutrient levels all interacting to create multiple plant stresses. Plant responses to abiotic stresses are dynamic and complex; they are both elastic (reversible) and plastic (irreversible), (Cramer et al., 2011), and many responses are heavily dependent on genetic susceptibility or tolerance.
Crop quality control and testing.
Authors: Morgan Lynette
Published: January 2021

Quality of horticultural produce and products implies suitability for a particular purpose, or the degree to which certain set standards are met. Aspects of produce quality may encompass sensory properties (appearance, texture, taste and aroma), nutritive values, chemical constituents, mechanical properties, functional properties and defects (Abbott, 1999). Fruit and vegetable production, being part of a larger biological system, is prone to a high degree of variability as factors such as climate, soils, crop management, and genetics all play a role in quality determination. Quality standards and testing methods have been developed for most commercial crops to help ensure consumers receive produce of a suitable standard. These quality standards can range from basic grading for removal of damaged produce and for size, shape, weight and overall appearance, to analytical testing for compositional factors such as acidity, volatiles, dry matter, starch and sugars, toxins, vitamins and minerals, and others. With increasing competition globally within the horticultural industry, and consumers growing interest in high quality, nutritious produce, compositional testing has become more widespread, both at a grower and postharvest level. While appearance is still vitally important in marketing and for consumer appeal at the point of sale, focus on other aspects of fruit and vegetable quality is becoming more prominent. These include not only organoleptic qualities of flavour and aroma, but also nutritional factors such as vitamin and minerals, fibre content and levels of phytoactive compounds such as antioxidants. Compositional quality also encompasses food safety and shelf life concerns such as the presence of nitrates in leafy greens, microbial contamination and naturally occurring toxins, with implications for human health and food-borne illness occurrence.
Diffusion of kinesin motors on cargo can enhance binding and run lengths during intracellular transport
Authors: Bovyn Matthew , Janakaloti Narayanareddy Babu Reddy , Gross Steven , Allard Jun
Published: January 2021

Computational simulation demonstrates that kinesin diffusion and mobility on the cargo surface can enhance intracellular transport by allowing both efficient initial binding and teamwork-induced long run lengths, compared with cargo without fluid surfaces.
AAV-mediated AP-1 decoy oligonucleotide expression inhibits aortic elastolysis in a mouse model of Marfan syndrome
Authors: Remes Anca , Arif Rawa , Franz Maximilian , Jungmann Andreas , Zaradzki Marcin , Puehler Thomas , Heckmann Markus B , Frey Norbert , Karck Matthias , Kallenbach Klaus , Hecker Markus , Müller Oliver J , Wagner Andreas H
Published: January 2021

Aims

Marfan syndrome is one of the most common inherited disorders of connective tissue caused by fibrillin-1 mutations, characterized by enhanced transcription factor AP-1 DNA binding activity and subsequently abnormally increased expression and activity of matrix-metalloproteinases (MMPs). We aimed to establish a novel adeno-associated virus (AAV)-based strategy for long-term expression of an AP-1 neutralizing RNA hairpin (hp) decoy oligonucleotide (dON) in the aorta to prevent aortic elastolysis in a murine model of Marfan syndrome.

Methods and results

Using fibrillin-1 hypomorphic mice (mgR/mgR), aortic grafts from young (9 weeks old) donor mgR/mgR mice were transduced ex vivo with AAV vectors and implanted as infrarenal aortic interposition grafts in mgR/mgR mice. Grafts were explanted after 30 days. For in vitro studies, isolated primary aortic smooth muscle cells (SMCs) from mgR/mgR mice were used. Elastica-van-Giesson staining visualized elastolysis, reactive oxygen species (ROS) production was assessed using dihydroethidine staining. RNA F.I.S.H. verified AP-1 hp dON generation in the ex vivo transduced aortic tissue. MMP expression and activity were assessed by western blotting and immunoprecipitation combined with zymography.

Transduction resulted in stable therapeutic dON expression in endothelial and SMCs. MMP expression and activity, ROS formation as well as expression of monocyte chemoattractant protein-1 were significantly reduced. Monocyte graft infiltration declined and the integrity of the elastin architecture was maintained. RNAseq analysis confirmed the beneficial effect of AP-1 neutralization on the pro-inflammatory environment in SMCs.

Conclusion

This novel approach protects from deterioration of aortic stability by sustained delivery of nucleic acids-based therapeutics and further elucidated how to interfere with the mechanism of elastolysis.
Successful percutaneous treatment of a catastrophic left internal mammary artery graft avulsion occurring 4 weeks post-coronary artery bypass grafting surgery: a case report
Authors: Tehrani Shana , Rathore Sudhir
Published: January 2021

Background

Avulsion of the left internal mammary artery (LIMA) graft near the anastomosis to the left anterior descending artery (LAD) artery post-coronary artery bypass grafting (CABG) is a rare but potentially catastrophic complication which can result in sudden ischaemia, haemodynamic compromise and life-threatening bleeding into the pericardium.

Case summary

We report a case of a spontaneous LIMA graft avulsion at the site of the anastomosis to the LAD artery, which occurred 4 weeks post-conventional CABG surgery and resulted in anterior myocardial infarction (MI), cardiac tamponade and cardiogenic shock. This life-threatening event was treated by deploying a covered stent in the LAD artery and by coiling the dehisced LIMA graft.

Discussion

To our knowledge, this is the first report of late LIMA graft avulsion that has been uniquely and successfully treated by percutaneous coronary intervention.
The cardiovascular effects of gonadotropin-releasing hormone antagonists in men with prostate cancer
Authors: Cirne Filipe , Aghel Nazanin , Petropoulos Jo-Anne , Klotz Laurence , Lenihan Daniel J , Saad Fred , Pinthus Jehonathan , Leong Darryl P
Published: January 2021

Aims

The aim of this study was to determine whether gonadotropin-releasing hormone (GnRH) antagonists (an emerging class of drugs to suppress testosterone synthesis in the treatment of prostate cancer) cause less adverse cardiovascular events than the more commonly use GnRH agonists.

Methods and results

We conducted a systematic review to identify all randomized, controlled trials in which a GnRH antagonist was compared with a GnRH agonist in men with prostate cancer. We identified 10 eligible studies including two different GnRH antagonists, degarelix (n = 1681) and relugolix (n = 734), which were compared with the GnRH agonists, leuprolide (n = 714) and goserelin (n = 600). The pooled risk ratios (95% confidence intervals) among GnRH antagonist recipients for adverse cardiovascular events, cardiovascular death, and all-cause mortality were 0.57 (0.39–0.81); 0.49 (0.25–0.96); and 0.48 (0.28–0.83), respectively. Important limitations of the included trials were their short duration of follow-up, unblinded study design and (in most of the studies) the identification of adverse cardiovascular events through safety reporting mechanisms rather than as a pre-specified outcome. There was no evidence of heterogeneity of findings among the studies.

Conclusions

There is consistent but methodologically limited data to suggest that GnRH antagonists—a relatively new class of androgen deprivation therapy for prostate cancer—cause significantly less cardiovascular adverse effects than the more frequently used GnRH agonists.
Motivational interviewing in a nurse-led outpatient clinic to support lifestyle behaviour change after admission to a stroke unit: a randomized controlled trial
Authors: Brouwer-Goossensen Dorien , Scheele Maaike , van Genugten Lenneke , Lingsma Hester F , Dippel Diederik W J , Koudstaal Peter J , den Hertog Heleen M
Published: January 2021

Aims

Modification of health behaviour is an important part of stroke risk management. However, the majority of people with cardiovascular disease fail to sustain lifestyle modification in the long term. We aimed to evaluate the effectiveness of motivational interviewing to encourage lifestyle behaviour changes after transient ischaemic attack (TIA) or minor ischaemic stroke.

Methods and results 

We performed a randomized controlled open-label phase II trial with blinded endpoint assessment. The intervention consisted of three 15-minute visits in 3 months by a motivational interviewing trained nurse practitioner. Patients in the control group received standard consultation after 1 and 3 months by a nurse practitioner. Primary outcome was lifestyle behaviour change, defined as smoking cessation and/or increased physical activity (30 min/day) and/or healthy diet improvement (5 points at the Food Frequency Questionnaire) at 6 months. We adjusted for age and sex with multivariable logistic regression. Between January 2014 and February 2016, we included 136 patients (of whom 68 were assigned to the intervention group). Twenty-five of 55 patients in the intervention group (45%) and 27 of 61 patients in the control group (44%) had changed their lifestyle at 6 months. We found no effect of motivational interviewing on lifestyle behaviour change after 6 months (aOR 0.99; 95% confidence interval: 0.44–2.26).

Conclusion 

Our results do not support the effectiveness of motivational interviewing in supporting lifestyle behaviour change after TIA or ischaemic stroke. However, the overall lifestyle behaviour change was high and might be explained by the role of specialized nurses in both groups.
Is Oxford Nanopore sequencing ready for analyzing complex microbiomes?
Authors: Kerkhof Lee J
Published: January 2021

This minireview will discuss the improvements in Oxford Nanopore (Oxford; sequencing technology that make the MinION a viable platform for microbial ecology studies. Specific issues being addressed are the increase in sequence accuracy from 65 to 96.5% during the last 5 years, the ability to obtain a quantifiable/predictive signal from the MinION with respect to target molecule abundance, simple-to-use GUI-based pathways for data analysis and the modest additional equipment needs for sequencing in the field. Coupling these recent improvements with the low capital costs for equipment and the reasonable per sample cost makes MinION sequencing an attractive option for virtually any laboratory.
Coevolution of the major histocompatibility complex and the t-complex in the mouse. I. Generation and maintenance of high complementarity associations.
Authors: Uyenoyama M K
Published: January 2021

A quantitative model is developed to explore the effects of prezygotic and postzygotic incompatibility on the origin and maintenance of associations between the major histocompatibility complex (MHC) and the t-complex in the mouse. Incompatibility is represented by a reduction in the rate of conception or gestation of offspring derived from sperm bearing MHC antigens in common with the mother. Incompatibility encourages the evolution of associations from a state of complete independence between the two complexes by promoting the invasion of all novel antigens, including those that exhibit associations with the t-complex. Incompatibility can modify the relative numbers of antigens associated with each haplotype by actively promoting the exclusion or invasion of recombinants that bear formerly +-specific or t-specific antigens on the alternative haplotype. The results of the analysis indicate that the state of complete independence between the MHC and the t-complex is not preserved over evolutionary time in the presence of incompatibility. Further, the expression of incompatibility maintains fully associated states that include a single antigen associated with the t-haplotype and up to three to five antigens associated with the +-haplotype within a single population.
Coevolution of the major histocompatibility complex and the t-complex in the mouse. II. Modification of response to sharing of histocompatibility antigens.
Authors: Uyenoyama M K
Published: January 2021

Selective pressures imposed by high complementarity associations between the major histocompatibility complex (MHC) and the t-complex on a locus that modifies the expression of prezygotic and postzygotic incompatibility are investigated through the analysis of a quantitative model. Sharing of MHC antigens between mates or between mother and offspring elicits weak inhibition of conception or gestation. In the presence of high complementarity associations between the MHC and the t-complex, weak incompatibility depresses the mean fitness of the population. Nevertheless, natural selection favors the enhancement of the expression of incompatibility if the number of antigens associated with the +-haplotype exceeds the number associated with the t-haplotype by a sufficient margin. Under absolute linkage between the modifier locus and the t-complex, the number associated with the +-haplotype need only be greater than the number associated with the t-haplotype. In the absence of linkage, a twofold difference is sufficient to ensure the initial increase of modifier alleles that intensify the expression of incompatibility.
Evolutionarily stable mutation rate in a periodically changing environment.
Authors: Ishii K , Matsuda H , Iwasa Y , Sasaki A
Published: January 2021

Evolution of mutation rate controlled by a neutral modifier is studied for a locus with two alleles under temporally fluctuating selection pressure. A general formula is derived to calculate the evolutionarily stable mutation rate mu(ess) in an infinitely large haploid population, and following results are obtained. (I) For any fluctuation, periodic or random: (1) if the recombination rate r per generation between the modifier and the main locus is 0, mu(ess) is the same as the optimal mutation rate mu(op) which maximizes the long-term geometric average of population fitness; and (2) for any r, if the strength s of selection per generation is very large, mu(ess) is equal to the reciprocal of the average number T of generations (duration time) during which one allele is persistently favored than the other. (II) For a periodic fluctuation in the limit of small s and r, mu(ess)T is a function of sT and rT with properties: (1) for a given sT, mu(ess)T decreases with increasing rT; (2) for sT </= 1, mu(ess)T is almost independent of sT, and depends on rT as mu(ess)T & 1.6 for rT < 1 and mu(ess)T & 6/rT for rT > 1; and (3) for sT >/= 1, and for a given rT, mu(ess)T decreases with increasing sT to a certain minimum less than 1, and then increases to 1 asymptotically in the limit of large sT. (III) For a fluctuation consisting of multiple Fourier components (i.e., sine wave components), the component with the longest period is the most effective in determining mu(ess) (low pass filter effect). (IV) When the cost c of preventing mutation is positive, the modifier is nonneutral, and mu(ess) becomes larger than in the case of neutral modifier under the same selection pressure acting at the main locus. The value of c which makes mu(ess) equal to mu(op) of the neutral modifier case is calculated. It is argued that this value gives a critical cost such that, so long as the actual cost exceeds this value, the evolution rate at the main locus must be smaller than its mutation rate mu(ess).
Molecular characterization of the Aspergillus nidulans yA locus.
Authors: O'Hara E B , Timberlake W E
Published: January 2021

We investigated the molecular organization of the region of Aspergillus nidulans chromosome I containing yA, a gene encoding the developmentally regulated enzyme conidial laccase. DNA fragments were identified that complemented the yA2 mutation and were shown to correspond to yA by genetic mapping and gene disruption experiments. The molecular map of the region was oriented to the genetic map by testing DNA fragments for their ability to complement a mutation in the tightly linked adE gene. The yA gene codes for a 2200 nucleotide mRNA that is present at low levels in vegetative cells and mature conidia, but accumulates to high levels in sporulating cultures. yA mRNA appears shortly after differentiation of sporogenous phialide cells. It accumulates in two developmentally abnormal mutant strains that produce phialides but is absent from two mutant strains that do not produce phialides. Thus, yA transcription is probably restricted to phialides. This result is discussed in relationship to the physiological roles played by phialides in spore differentiation.
Organelle gene diversity under migration, mutation, and drift: equilibrium expectations, approach to equilibrium, effects of heteroplasmic cells, and comparison to nuclear genes.
Authors: Birky C W , Fuerst P , Maruyama T
Published: January 2021

We developed stochastic population genetic theory for mitochondrial and chloroplast genes, using an infinite alleles model appropriate for molecular genetic data. We considered the effects of mutation, random drift, and migration in a finite island model on selectively neutral alleles. Recurrence equations were obtained for the expectation of gene diversities within zygotes, within colonies, and between colonies. The variables are number and sizes of colonies, migration rates, sex ratios, degree of paternal transmission, number of germ line cell divisions, effective number of segregating organelle genomes, and mutation rate. Computer solutions of the recurrence equations were used to study the approach to equilibrium. Gene diversities equilibrate slowly, while GST, used to measure population subdivision, equilibrates rapidly. Approximate equilibrium equations for gene diversities and GST can be obtained by substituting Neo and me, simple functions of the numbers of breeding or migrating males and females and of the degree of paternal transmission, for the effective numbers of genes and migration rates in the corresponding equations for nuclear genes. The approximate equations are not valid when the diversity within individuals is large compared to that between individuals, as is often true for the D-loop of animal mtDNA. We used the exact equations to verify that organelle genes often show more subdivision than nuclear genes; however, we also identified the range of breeding and migrating sex ratios for which population subdivision is greater for nuclear genes. Finally, we show that gene diversities are higher for nuclei than for organelles over a larger range of sex ratios in a subdivided population than in a panmictic population.
Co-localization to chromosome bands 99E1-3 of the Drosophila melanogaster myosin light chain-2 gene and a haplo-insufficient locus that affects flight behavior.
Authors: Warmke J W , Kreuz A J , Falkenthal S
Published: January 2021

Using overlapping synthetic deficiencies, we find that a haplo-insufficient locus affecting flight behavior and the myosin light chain-2 gene co-map to the Drosophila melanogaster polytene chromosome interval 99D9-E1 to 99E2-3. From screening over 9000 EMS-treated chromosomes, we obtained alleles of two complementation groups that map to this same interval. One of these complementation groups lfm(3)99Eb, exhibits dominant flightless behavior; thus, flightless behavior of the deficiency is in all likelihood due to hemizygosity of this single locus. Rescue of flightless behavior by a duplication indicates that the single allele, E38, of the Ifm(3)99Eb complementation group is a hypomorph. Based upon its map position and a reduction in concentration of myosin light chain-2 mRNA in heterozygotes, we propose that Ifm(3)Eb(E38) is a mutant allele of the myosin light chain-2 gene. Our genetic analysis also resulted in the identification of four dominant flightless alleles of an unlinked locus, l(3)nc99Eb, that exhibits dominant lethal synergism with Ifm(3)99Eb.
A comprehensive genetic map of murine chromosome 11 reveals extensive linkage conservation between mouse and human.
Authors: Buchberg A M , Brownell E , Nagata S , Jenkins N A , Copeland N G
Published: January 2021

Interspecific backcross animals from a cross between C57BL/6J and Mus spretus mice were used to generate a comprehensive linkage map of mouse chromosome 11. The relative map positions of genes previously assigned to mouse chromosome 11 by somatic cell hybrid or genetic backcross analysis were determined (Erbb, Rel, 11-3, Csfgm, Trp53-1, Evi-2, Erba, Erbb-2, Csfg, Myhs, Cola-1, Myla, Hox-2 and Pkca). We also analyzed genes that we suspected would map to chromosome 11 by virtue of their location in human chromosomes and the known linkage homologies that exist between murine chromosome 11 and human chromosomes (Mpo, Ngfr, Pdgfr and Fms). Two of the latter genes, Mpo and Ngfr, mapped to mouse chromosome 11. Both genes also mapped to human chromosome 17, extending the degree of linkage conservation observed between human chromosome 17 and mouse chromosome 11. Pdgfr and Fms, which are closely linked to II-3 and Csfgm in humans on chromosome 5, mapped to mouse chromosome 18 rather than mouse chromosome 11, thereby defining yet another conserved linkage group between human and mouse chromosomes. The mouse chromosome 11 linkage map generated in these studies substantially extends the framework for identifying homologous genes in the mouse that are involved in human disease, for elucidating the genes responsible for several mouse mutations, and for gaining insights into chromosome evolution and genome organization.
Multivariate mutation-selection balance with constrained pleiotropic effects.
Authors: Wagner G P
Published: January 2021

A multivariate quantitative genetic model is analyzed that is based on the assumption that the genetic variation at a locus j primarily influences an underlying physiological variable yj, while influence on the genotypic values is determined by a kind of "developmental function" which is not changed by mutations at this locus. Assuming additivity among loci the developmental function becomes a linear transformation of the underlying variables y onto the genotypic values x, x = By. In this way the pleiotropic effects become constrained by the structure of the B-matrix. The equilibrium variance under mutation-stabilizing selection balance in infinite and finite populations is derived by using the house of cards approximation. The results are compared to the predictions given by M. Turelli in 1985 for pleiotropic two-character models. It is shown that the B-matrix model gives the same results as Turelli's five-allele model, suggesting that the crucial factor determining the equilibrium variance in multivariate models with pleiotropy is the assumption about constraints on the pleiotropic effects, and not the number of alleles as proposed by Turelli. Finally it is shown that under Gaussian stabilizing selection the structure of the B-matrix has effectively no influence on the mean equilibrium fitness of an infinite population. Hence the B-matrix and consequently to some extent also the structure of the genetic correlation matrix is an almost neutral character. The consequences for the evolution of genetic covariance matrices are discussed.
The yeast RAD50 gene encodes a predicted 153-kD protein containing a purine nucleotide-binding domain and two large heptad-repeat regions.
Authors: Alani E , Subbiah S , Kleckner N
Published: January 2021

The RAD50 gene of Saccharomyces cerevisiae is required for chromosome synapsis and recombination during meiosis and for repair of DNA damage during vegetative growth. The precise role of the RAD50 gene product in these processes is not known. Most rad50 mutant phenotypes can be explained by the proposal that the RAD50 gene product is involved in the search for homology between interacting DNA molecules or chromosomes, but there is no direct evidence for this model. We present here the nucleotide sequence of the RAD50 locus and an analysis of the predicted 153-kD RAD50 protein. The amino terminal region of the predicted protein contains residues suggestive of a purine nucleotide binding domain, most likely for adenine. The remaining 1170 amino acids consist of two 250 amino acid segments of heptad repeat sequence separated by 320 amino acids, plus a short hydrophobic carboxy-terminal tail. Heptad repeats occur in proteins such as myosin and intermediate filaments that form alpha-helical coiled coils. One of the two heptad regions in RAD50 shows similarity to the S-2 domain of rabbit myosin beyond that expected for two random coiled coil proteins.
A large cluster of highly expressed genes is dispensable for growth and development in Aspergillus nidulans.
Authors: Aramayo R , Adams T H , Timberlake W E
Published: January 2021

We investigated the functions of the highly expressed, sporulation-specific SpoC1 genes of Aspergillus nidulans by deleting the entire 38-kb SpoC1 gene cluster. The resultant mutant strain did not differ from the wild type in (1) growth rate, (2) morphology of specialized reproductive structures formed during completion of the asexual or sexual life cycles, (3) sporulation efficiency, (4) spore viability or (5) spore resistance to environmental stress. Thus, deletion of the SpoC1 gene cluster, representing 0.15% of the A. nidulans genome, had no readily detectable phenotypic effects. Implications of this result are discussed in the context of major alterations in gene expression that occur during A. nidulans development.
Characterization of the amdR-controlled lamA and lamB genes of Aspergillus nidulans.
Authors: Katz M E , Hynes M J
Published: January 2021

Four Aspergillus nidulans genes are known to be under the control of the trans-acting regulatory gene amdR. We describe the isolation and initial characterization of one of these amdR-regulated genes, lamA. The lam locus, however, was found to consist of two divergently transcribed genes, the lamA gene, and a new gene, also under amdR control, which we have designated lamB. Using recombinant DNA techniques we have constructed a strain of A. nidulans lacking a functional lamB gene. Experiments conducted with this strain demonstrate that lamB, like lamA, is involved in utilization of 2-pyrrolidinone in A. nidulans. Metabolism of a related compound, gamma-amino butyric acid (GABA) is not affected. We also provide evidence that the conversion of exogenous 2-pyrrolidinone to endogenous GABA requires a functional lamB gene. The expression of both lamA and lamB is subject to carbon and nitrogen metabolite repression in addition to amdR-mediated induction by omega-amino acids.
Rapid spread of transposable p elements in experimental populations of Drosophila melanogaster.
Authors: Good A G , Meister G A , Brock H W , Grigliatti T A , Hickey D A
Published: January 2021

The invasion of P elements in natural populations of Drosophila melanogaster was modeled by establishing laboratory populations with 1%, 5% and 10% P genomes and monitoring the populations for 20 generations. In one experiment, the ability of flies to either induce or suppress gonadal sterility in different generations was correlated with the amount of P element DNA. In a second experiment, the percentage of genomes that contained P elements, and the distribution of P elements among individual flies was monitored. The ability to induce gonadal dysgenesis increased rapidly each generation. However, the increase in P cytotype lagged behind by five to ten generations. The total amount of P element DNA and the frequency of flies containing P elements increased each generation. The number of P elements within individual genomes decreased initially, but then increased. Finally, the distribution of P elements within the genomes of individuals from later generations varied considerably, and this pattern differed from the parental P strain. These results suggest that the interaction between the assortment and recombination of chromosomal segments, and multiplicative transposition could result in the rapid spread of P elements in natural populations.
Genetic definition of two functional elements in a bacteriophage T4 host-range "cassette".
Authors: Snyder M , Wood W B
Published: January 2021

Gene 37 of T4 encodes the major subunit of the distal half of the tail fiber. The distal tip of the fiber, comprised of the carboxy-terminal ends of two molecules of gene 37 product (gp37), carries the principal determinant of the phage host range. The gp37 carboxyl termini recognize the bacterial surface during infection, and, in addition, include a site required for interaction with the product of gp38 during distal half-fiber assembly. In the absence of interaction with gp38, gp37 polypeptides do not dimerize. Eleven temperature-sensitive mutants with defects located near the promoter-distal end of gene 37 were tested at nonpermissive temperatures for production of an antigen that is diagnostic of distal half-fiber assembly. Six of the mutations prevent distal half-fiber assembly. The other five allow assembly of distal half fibers, which combine with proximal half fibers and attach to phage particles, but the resulting phage do not adsorb to bacteria. These two classes of mutations define two adjacent but separate genetic regions, corresponding to two different functional domains in gp37. These two regions and the neighboring gene 38 comprise a functional unit that can be considered as a host-range "cassette," with features that are strikingly similar to corresponding functional units in other unrelated as well as related phages.
Genic and allelic interactions in the carotenogenic response of myxococcus xanthus to blue light.
Authors: Martinez-Laborda A , Murillo F J
Published: January 2021

In the bacterium Myxococcus xanthus, the synthesis of carotenoids requires illumination with blue light. This stimulates transcription of the carB locus, which is positively required for carotenogenesis. Mutations at the carR locus and the only mutation known at carA cause constitutive expression of carB and thus remove the light requirement for carotenoid accumulation (Car(c) phenotype). The carR locus is unlinked, and carA is linked, to carB. We have now identified a novel class of car mutation, closely linked to carR, that block accumulation of carotenoids and transcription of carB, and are epistatic over the Car(c) mutations at carR but not over the Car(c) mutation at carA. We also report here the cloning of a 16-kb DNA fragment that contains the entire carA gene in a shuttle vector for DNA transfer between Escherichia coli and M. xanthus. The study of allelic interactions at this gene strongly indicate that carA is a cis-acting element for the control of carB expression. A regulatory model that satisfies all the indicated data is presented.
Cloning and characterization of the scarlet gene of Drosophila melanogaster.
Authors: Tearle R G , Belote J M , McKeown M , Baker B S , Howells A J
Published: January 2021

DNA from the scarlet (st) region of Drosophila melanogaster has been cloned by chromosome walking, using the breakpoints of a new X-ray-induced third chromosome inversion (In(3LR)st-a27) which breaks in the scarlet (73A3.4) and rosy (87D13-14) regions. Two spontaneous mutants of st(st1 and stsp) contain insertions of non-st DNA located within 3.0 kb of the site of the inversion breakpoint used to isolate the gene, and a second scarlet inversion breaks within 6.5 kb of this site. However no changes detectable by Southern blotting were found in 5 X-ray-induced st mutants with cytologically normal third chromosomes. A 2.3-kb transcript arising from the st gene region (as defined by mutant analysis and DNA transformation) has been detected. This transcript is present throughout development at low levels, with a peak level during the early to mid-pupal stage. The size and amount of this transcript is altered in st1, and its amount is drastically reduced in stsp. Flies carrying the white1 mutation show normal levels of expression of the st transcript, suggesting that the w+ gene does not regulate transcription of the st+ gene. Nucleotide homology between sequences from the st transcription unit and a fragment carrying coding information from the white gene has been detected. This suggests that the st and w proteins are related; they appear to belong to a family of membrane-spanning, ATP-binding proteins involved in the transport of pigment precursors into cells.
Is knowing the age-order of alleles in a sample useful in testing for selective neutrality?
Authors: Tavaré S , Ewens W J , Joyce P
Published: January 2021

The most powerful, and most frequently used, test of selective neutrality, based on data consisting of observed allelic frequencies in a sample of genes at some locus, is the procedure of G. A. Watterson. This procedure uses the sample homozygosity F* as the test statistic, and in effect leads to rejection of the hypothesis of selective neutrality if the observed value of F* differs significantly from neutral theory expectations. The homozygosity statistic is invariant under relabeling of the alleles and thus cannot use any further information on the alleles which might be available. We present results which suggest that information concerning the age order of the alleles cannot be used to provide a more powerful testing procedure than that of Watterson.
Genetic correlations and maternal effect coefficients obtained from offspring-parent regression.
Authors: Lande R , Price T
Published: January 2021

Additive genetic variances and covariances of quantitative characters are necessary to predict the evolutionary response of the mean phenotype vector in a population to natural or artificial selection. Standard formulas for estimating these parameters, from the resemblance between relatives in one or two characters at a time, are biased by natural selection on the parents and by maternal effects. We show how these biases can be removed using a multivariate analysis of offspring-parent regressions. A dynamic model of maternal effects demonstrates that, in addition to the phenotypic variance-covariance matrix of the characters, sufficient parameters for predicting the response of the mean phenotype vector to weak selection are the additive genetic variance-covariance matrix and a set of causal coefficients for maternal effects. These can be simultaneously estimated from offspring-parent regressions alone, in some cases just from the daughter-mother regressions, if all of the important selected and maternal characters have been measured and included in the analysis.
Role of gene duplications in the adaptation of Salmonella typhimurium to growth on limiting carbon sources.
Authors: Sonti R V , Roth J R
Published: January 2021

Duplication-containing cells are selected when growth of Salmonella typhimurium is limited by the availability of any one of several carbon and energy sources. Under conditions of extreme starvation, growth occurs almost exclusively in the duplication-containing fraction of the population. Cells with duplications of one large segment of the chromosome are repeatedly selected regardless of which of these carbon sources limits growth. The duplicated chromosomal segment encodes the transport systems for all of these carbon sources. This duplication is not selected during growth on a carbon source for which the permease is not included within the duplication segment. This suggests that the growth advantage conferred by the duplication may be due to increased transport of the limiting carbon source. Inclusion of the permease alone is not sufficient to explain the growth advantage of the duplications, since other common duplications that include the permease are not selected.
Position effects in ectopic and allelic mitotic recombination in Saccharomyces cerevisiae.
Authors: Lichten M , Haber J E
Published: January 2021

We have examined the role that genomic location plays in mitotic intragenic recombination. Mutant alleles of the LEU2 gene were inserted at five locations in the yeast genome. Diploid and haploid strains containing various combinations of these inserts were used to examine both allelic recombination (between sequences at the same position on parental homologs) and ectopic recombination (between sequences at nonallelic locations). Chromosomal location had little effect on mitotic allelic recombination. The rate of recombination to LEU2 at five different loci varied less than threefold. This finding contrasts with previous observations of strong position effects in meiosis; frequencies of meiotic recombination at the same five loci differ by about a factor of forty. Mitotic recombination between dispersed copies of leu2 displayed strong position effects. Copies of leu2 located approximately 20 kb apart on the same chromosome recombined at rates 6-13-fold higher than those observed for allelic copies of leu2. leu2 sequences located on nonhomologous chromosomes or at distant loci on the same chromosome recombined at rates similar to those observed for allelic copies. We suggest that, during mitosis, parental homologs interact with each other no more frequently than do nonhomologous chromosomes.
Xanthine dehydrogenase is transported to the Drosophila eye.
Authors: Reaume A G , Clark S H , Chovnick A
Published: January 2021

The rosy (ry) locus in Drosophila melanogaster codes for the enzyme xanthine dehydrogenase. Mutants that have no enzyme activity are characterized by a brownish eye color phenotype reflecting a deficiency in the red eye pigment. This report demonstrates that enzyme which is synthesized in some tissue other than the eye is transported and sequestered at the eye. Previous studies find that no leader sequence is associated with this molecule but a peroxisomal targeting sequence has been noted, and the enzyme has been localized to peroxisomes. This represents a rare example of an enzyme involved in intermediary metabolism being transported from one tissue to another and may also be the first example of a peroxisomal protein being secreted from a cell.
Interactions between pesticide genes: model and experiment.
Authors: Raymond M , Heckel D G , Scott J G
Published: January 2021

In response to years of intense selection pressure by organophosphate insecticides, several different insecticide resistance mechanisms have evolved in natural populations of the mosquito Culex pipiens. We examined interactions between two of the most important mechanisms using a four-compartment model of insecticide pharmacokinetics. The joint effect of different mechanisms of resistance can be expressed in terms of epistasis at the physiological level in this model. The type of epistasis predicted by the model depends on the particular physiological mechanisms of resistance involved. Resistance due to a reduced penetration of the insecticide combines multiplicatively with other resistance factors, but resistance due to detoxicative processes and to insensitivity of the target site combines additively. How the pattern of epistasis at the physiological level is translated into fitness epistasis in natural populations of this mosquito depends on the intensity and pattern of insecticide selection in the field.
No linkage between genes controlling female pheromone production and male pheromone response in the European corn borer, Ostrinia nubilalis Hübner (Lepidoptera; Pyralidae).
Authors: Löfstedt C , Hansson B S , Roelofs W , Bengtsson B O
Published: January 2021

The E and Z pheromonal strains of the European corn borer, Ostrinia nubilalis, are characterized by female production of and male preference for opposite blends of (E)-11-and (Z)-11-tetradecenyl acetate. It is known that the pheromone production is controlled by an autosomal gene and that the males' behavior is determined by a sex-linked gene. A third gene, autosomally inherited, has been shown to determine the organization of the male pheromone receptors. In the present study the linkage relationship between the autosomal genes controlling sex pheromone production and male olfactory sensilla was investigated. A recombination experiment showed unequivocally that the genes determining the variation in pheromone production and male pheromone receptors are not closely linked and are most likely inherited independently.
Molecular and genetic characterization of Mu transposable elements in Zea mays: behavior in callus culture and regenerated plants.
Authors: Planckaert F , Walbot V
Published: January 2021

Active Mutator lines of maize (Zea mays L.) have a high mutation rate and contain multiple hypomethylated 1.4-kb and 1.7-kb Mu transposable elements. Correlated with the inactivation of the Mutator system, these Mu elements cease to transpose and become more methylated. To determine whether the shock of tissue culture can affect Mutator activities, F1 progenies of outcrosses between active or inactive Mutator stocks and inbred line A188 were used to initiate embryogenic callus cultures. HinfI restriction digestion of genomic DNA isolated from 3-5-month-old cultures demonstrated that there is a very good correlation between the modification state of Mu elements in the cultures and the Mutator parent. Despite the dedifferentiation and rapid proliferation characteristic of tissue culture, the Mutator activity state is relatively stable during an extended tissue culture period. Cultures established from inactive Mutator lines were not reactivated; cultures established from active lines maintained a high Mu copy number, and most Mu elements remained unmodified. In contrast, weakly active Mutator parents gave rise to cultures in which Mu element modification could switch between low and high methylation during the culture period. Evidence for transposition was investigated with EcoRI digestion of genomic DNA isolated at different times during culture. The appearance of novel Mu-hybridizing fragments and a strong background hybridization are interpreted as evidence that transposition events occur during culture. Plants regenerated from such active cultures transmitted Mutator activity to their progeny.