scholarly journals GERMLINE HYPERMUTABILITY IN DROSOPHILA AND ITS RELATION TO HYBRID DYSGENESIS AND CYTOTYPE

Genetics ◽  
1981 ◽  
Vol 98 (3) ◽  
pp. 565-587
Author(s):  
William R Engels
Keyword(s):  
Cell Survival ◽  
Chromosomal Rearrangements ◽  
Stable State ◽  
Hybrid Dysgenesis ◽  
Mutation Rates ◽  
Female Sterility ◽  
Genetic Element ◽  
Two Generations ◽  
The Mean ◽  
P Factor

ABSTRACT In its hypermutable state, an unstable singed allele, snw, mutates in the germline to two other alleleic forms at a total frequency usually between 40 and 60%. In its stable state, the mutation rate of snw is essentially zero. Its state depends on an extrachromosomal condition indistinguishable from a property called cytotype previously studied as a component of hybrid dysgenesis. Of the two known systems of hybrid dysgenesis, denoted P-M and I-R, snw hypermutability is determined by the P-M system and appears to be independent of the I-R system. Cytotype, as defined by the control of snw mutability, is self-reproducing in the cytoplasm or nucleoplasm of the germline through at least two generations. However, it is not entirely autonomous, being ultimately determined by the chromosomes after sufficiently many generations of backcrossing. This combination of chromosomal and extrachromosomal transmission agrees well with previous studies on cytotype. Temperature differences have little effect on the mean mutation rates, but they have a pronounced effect on the intrinsic variance among individuals. The latter effect suggests that high temperatures reduce germ-cell survival during the development of dysgenic flies. Chromosomal rearrangements produce no apparent effects on the behavior of snw. Hypermutability is thought to be caused by the excision or other alteration of an inserted genetic element in the snw gene. This element might be a copy of the "P factor," which is though to be a mobile sequence capable of causing female sterility and other dysgenic traits in the P-M system.

scholarly journals Further Analysis of Hybrid Dysgenesis in Drosophila melanogaster

1982 ◽  
Vol 35 (5) ◽  
pp. 533 ◽  
Author(s):  
DJ Colgan ◽  
JA Sved
Keyword(s):  
Critical Period ◽  
Reciprocal Cross ◽  
Temperature Shift ◽  
Hybrid Dysgenesis ◽  
Transmission Ratio Distortion ◽  
Genetic Element ◽  
Critical Periods ◽  
Ratio Distortion ◽  
P Factor ◽  
Few Data

A systematic survey of the sterility of second-generation females produced by backcrossing hybrids of dysgenically interacting strains of D. melanogaster is reported. The effects of Fl rearing temperature and chromosomal constitution on this sterility were explicable in terms of the regulation of a transposable, inserted genetic element called the P factor which is known to be associated with hybrid dysgenesis. No applied radiation or chemical treatment induced dysgenic aberrations where they would not normally be found but, where they were found, EDT A slightly increased and ultraviolet radiation reduced their intensity. The results of previous temperature-shift experiments have implicated different periods during development as having the most effect on female'fertility. The present studies show little effect of interstrain variation on this critical period. Critical periods are identified for male sterility and recombination. Transmission ratio distortion has been shown to occur only in one of the reciprocal-cross hybrids (M x P) of parental strains causing dysgenesis. The degree of distortion in such crosses is shown here to vary between M strains crossed to the same P strain. Few data are available for the second (P x M) cross. The data reported here confirm that whatever distortion occurs in this cross is slight.

Artificial and Epigenetic Regulation of the I Factor, a Nonviral Retrotransposon of Drosophila melanogaster

Genetics ◽  
2000 ◽  
Vol 156 (4) ◽  
pp. 1867-1878 ◽  
Author(s):  
Emmanuel Gauthier ◽  
Christophe Tatout ◽  
Hubert Pinon
Keyword(s):  
Drosophila Melanogaster ◽  
Maternal Effect ◽  
Copy Number ◽  
Hybrid Dysgenesis ◽  
Female Sterility ◽  
Paternal Effects ◽  
Transgene Copy Number ◽  
Paternal Effect ◽  
Two Generations ◽  
I Factor

Abstract The I factor (IF) is a LINE-like transposable element from Drosophila melanogaster. IF is silenced in most strains, but under special circumstances its transposition can be induced and correlates with the appearance of a syndrome of female sterility called hybrid dysgenesis. To elucidate the relationship between IF expression and female sterility, different transgenic antisense and/or sense RNAs homologous to the IF ORF1 have been expressed. Increasing the transgene copy number decreases both the expression of an IF-lacZ fusion and the intensity of the female sterile phenotype, demonstrating that IF expression is correlated with sterility. Some transgenes, however, exert their repressive abilities not only through a copy number-dependent zygotic effect, but also through additional maternal and paternal effects that may be induced at the DNA and/or RNA level. Properties of the maternal effect have been detailed: (1) it represses hybrid dysgenesis more efficiently than does the paternal effect; (2) its efficacy increases with both the transgene copy number and the aging of sterile females; (3) it accumulates slowly over generations after the transgene has been established; and (4) it is maintained for at least two generations after transgene removal. Conversely, the paternal effect increases only with female aging. The last two properties of the maternal effect and the genuine existence of a paternal effect argue for the occurrence, in the IF regulation pathway, of a cellular memory transmitted through mitosis, as well as through male and female meiosis, and akin to epigenetic phenomena.

scholarly journals Use of an Insulation-Tipped Knife during Rigid Bronchoscopic Treatment of Benign Tracheobronchial Stenosis

Medicina ◽  
2021 ◽  
Vol 57 (3) ◽  
pp. 251
Author(s):  
Ji-Won Park ◽  
Yousang Ko ◽  
Changhwan Kim
Keyword(s):  
Tracheal Stenosis ◽  
Treatment Success ◽  
Stable State ◽  
Forced Expiratory Volume ◽  
Rigid Bronchoscopy ◽  
Bronchial Stenosis ◽  
Tracheobronchial Stenosis ◽  
Acute Complications ◽  
The Mean ◽  
Post Intubation

Background and Objectives: Tracheal or bronchial tears are potential complications of rigid bronchoscopy. This study aimed to investigate the acute complications and outcomes of using an insulation-tipped (IT) knife in combination with rigid bronchoscopic dilatation for treating benign tracheobronchial stenosis. Materials and Methods: We conducted a chart review of patients with benign tracheobronchial stenosis who were treated with rigid bronchoscopy and an IT knife at two referral centers. Treatment success was defined as a clinically stable state without worsening symptoms after 3 months of treatment. Results: Of the 23 patients with benign tracheobronchial stenosis, 15 had tracheal stenosis and 6 had main bronchial stenosis. Among them, three cases were of simple stenosis (13%), while the others were of complex stenosis (87%). The overall treatment success rate was 87.0%. Pneumomediastinum and subcutaneous emphysema occurred due to bronchial laceration in two cases of distal left main bronchial stenosis (8.7%), and no other significant acute complications developed. Silicone stents were inserted in 20 patients, and successful stent removal was possible in 11 patients (55.0%). Six of the seven stents inserted in patients with post-intubation tracheal stenosis were removed successfully (85.7%). However, most of the patients with post-tracheostomy tracheal stenosis required persistent stenting (80%). Pulmonary function was significantly increased after treatment, and the mean increase in the forced expiratory volume in 1 s was 391 ± 171 mL (160–700 mL). Conclusion: The use of an IT knife can be suggested as an effective and safe modality for rigid bronchoscopic treatment of benign tracheobronchial stenosis.

scholarly journals The mutation load under tetrasomic inheritance and its consequences for the evolution of the selfing rate in autotetraploid species

1999 ◽  
Vol 74 (1) ◽  
pp. 31-42 ◽  
Author(s):  
J. RONFORT
Keyword(s):  
Inbreeding Depression ◽  
Deleterious Mutation ◽  
Stable State ◽  
Approximate Solutions ◽  
Balance Model ◽  
Deleterious Mutations ◽  
Selfing Rate ◽  
Mutation Load ◽  
Mean Fitness ◽  
The Mean

Single-locus equilibrium frequencies of a partially recessive deleterious mutation under the mutation–selection balance model are derived for partially selfing autotetraploid populations. Assuming multiplicative fitness interactions among loci, approximate solutions for the mean fitness and inbreeding depression values are also derived for the multiple locus case and compared with expectations for the diploid model. As in diploids, purging of deleterious mutations through consanguineous matings occurs in autotetraploid populations, i.e. the equilibrium mutation load is a decreasing function of the selfing rate. However, the variation of inbreeding depression with the selfing rate depends strongly on the dominance coefficients associated with the three heterozygous genotypes. Inbreeding depression can either increase or decrease with the selfing rate, and does not always vary monotonically. Expected issues for the evolution of the selfing rate consequently differ depending on the dominance coefficients. In some cases, expectations for the evolution of the selfing rate resemble expectations in diploids; but particular sets of dominance coefficients can be found that lead to either complete selfing or intermediate selfing rates as unique evolutionary stable state.

scholarly journals Assessment of the prevalence of vertical hepatitis B transmission in two consecutive generations

2018 ◽  
Vol 64 (2) ◽  
pp. 154-158
Author(s):  
Larissa Akeme Nakano ◽  
Jéssica Toshie Katayose ◽  
Rodrigo Martins Abreu ◽  
Luis Cláudio Alfaia Mendes ◽  
Maria Cleusa Martins ◽  
...  
Keyword(s):  
Hepatitis B ◽  
Vertical Transmission ◽  
Preventive Measures ◽  
Public Health Problem ◽  
Cross Sectional Study ◽  
Important Public Health Problem ◽  
Cross Sectional ◽  
Two Generations ◽  
Hepatitis B Transmission ◽  
The Mean

Summary Introduction: Hepatitis B is an important public health problem in the world and one of the forms of contagion would be through vertical transmission. Precose diagnosis allows the adoption of prophylaxis measures, which results in prevention in more than 90% of cases. Objective: To describe the prevalences of vertical transmission and compare two generations (mother/patient and patient/child). Method: This was a cross-sectional study, which included 101 patients. The interviews were performed through the application of the instrument of data collection and information of the physical file before the medical consultation. Results: The mean ± SD of age was 50.9 ± 13.1 years, the male gender predominated, with 56.4% of the patients, and the predominance was white, with 43.6%. Vertical transmission between mother and patient occurred in 17.8% and between patient and child, in 7.9%. In all of the eight cases of vertical transmission, the diagnosis was after the birth of children infected with HBV, and in 3/8 (37.5%), there was more than one case of infection by this mechanism per patient, totaling 13 children with the disease. Conclusion: There was a reduction in vertical transmission, showing that preventive measures were effective.

scholarly journals Effect of Hybridization on Somatic Mutations and Genomic Rearrangements in Plants

2018 ◽  
Vol 19 (12) ◽  
pp. 3758 ◽  
Author(s):  
Tufail Bashir ◽  
Ratnesh Chandra Mishra ◽  
Md. Hasan ◽  
Tapan Mohanta ◽  
Hanhong Bae
Keyword(s):  
Genome Size ◽  
Crop Yield ◽  
Somatic Mutation ◽  
Somatic Mutations ◽  
Chromosomal Rearrangements ◽  
Hybrid Vigor ◽  
Genomic Rearrangements ◽  
Mutation Rates ◽  
Hybrid Offspring ◽  
Hybrid Plants

Hybridization has been routinely practiced in agriculture to enhance the crop yield. Principally, it can cause hybrid vigor where hybrid plants display increased size, biomass, fertility, and resistance to diseases, when compared to their parents. During hybridization, hybrid offspring receive a genomic shock due to mixing of distant parental genomes, which triggers a myriad of genomic rearrangements, e.g., transpositions, genome size changes, chromosomal rearrangements, and other effects on the chromatin. Recently, it has been reported that, besides genomic rearrangements, hybridization can also alter the somatic mutation rates in plants. In this review, we provide in-depth insights about hybridization triggered genomic rearrangements and somatic mutations in plants.

scholarly journals Non-mendelian female sterility in Drosophila melanogaster: variations of chromosomal contamination when caused by chromosomes of various inducer efficiencies

1978 ◽  
Vol 32 (2) ◽  
pp. 113-122 ◽  
Author(s):  
Alain Pélisson
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Recombination ◽  
Laboratory Strain ◽  
The Other ◽  
Female Sterility ◽  
Genetic Element ◽  
Specific Kind ◽  
Classical Genetic ◽  
Apparent Change

SUMMARYA quite specific kind of sterile F1 female, called SF females, arises only when females of strains denoted reactive are crossed with males of the other class (inducer). It was previously shown that this sterility results from a nucleocytoplasmic interaction between the maternal reactive cytoplasm and a factor, called I, which may be born by any one of the paternal chromosomes. In SF females, but not in their brothers, a varying proportion of reactive chromosomes are able to acquire irreversibly the I factor, independently of any classical genetic recombination with the inducer chromosome(s). During this process, called chromosomal contamination, the contaminating chromosome(s) do not undergo any apparent change. The present paper deals with the efficiency of both original inducer and contaminated chromosomes to yield a more or less intense SF sterility. The Otanu inducer laboratory strain contains at least two types of X chromosomes (called strong and weak) which differ genetically with respect to their inducer efficiency. Reactive third chromosomes were contaminated by these strong or weak X chromosomes and their inducer efficiencies compared. Results show that they are on average stronger when they have been contaminated by strong X chromosomes than when contaminated by weak ones. Such a correlation favours the hypothesis that chromosomal contamination is due to the insertion of some genetic element(s) into reactive chromosomes.

Temporal and Spatial Variations of Wall Shear Stress in the Entrance Region of Microvessels

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Othmane Oulaid ◽  
Junfeng Zhang
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Stable State ◽  
Entrance Region ◽  
Channel Inlet ◽  
Long Distance ◽  
The Mean ◽  
Temporal And Spatial ◽  
Wall Shear ◽  
Cell Free Layer

Using a simplified two-dimensional divider-channel setup, we simulate the development process of red blood cell (RBC) flows in the entrance region of microvessels to study the wall shear stress (WSS) behaviors. Significant temporal and spatial variation in WSS is noticed. The maximum WSS magnitude and the strongest variation are observed at the channel inlet due to the close cell-wall contact. From the channel inlet, both the mean WSS and variation magnitude decrease, with a abrupt drop in the close vicinity near the inlet and then a slow relaxation over a relatively long distance; and a relative stable state with approximately constant mean and variation is established when the flow is well developed. The correlations between the WSS variation features and the cell free layer (CFL) structure are explored, and the effects of several hemodynamic parameters on the WSS variation are examined. In spite of the model limitations, the qualitative information revealed in this study could be useful for better understanding relevant processes and phenomena in the microcirculation.

scholarly journals Comparison of the regulation of P elements in M and M′ strains of Drosophila melanogaster

1989 ◽  
Vol 54 (1) ◽  
pp. 13-22 ◽  
Author(s):  
Stéphane Ronsseray ◽  
Monique Lehmann ◽  
Georges Periquet
Keyword(s):  
Drosophila Melanogaster ◽  
Copy Number ◽  
Gonadal Dysgenesis ◽  
Mixed Cultures ◽  
Hybrid Dysgenesis ◽  
P Elements ◽  
Copy Numbers ◽  
P Factor ◽  
P Type

SummaryM and M′ strains of Drosophila melanogaster in the P-M system of hybrid dysgenesis were compared in two series of tests, with the following results. (1) The singed-weak hypermutability regulation test showed that M′ strains had lower P excision rates than M strains, suggesting that P-elements repression must occur in M′ strains although it is not detectable by gonadal dysgenesis assays. (2) The evolution of mixed P + M and mixed P + M′ populations was compared, using a strong P strain. The P + M cultures invariably evolved in a few generations into strong P cultures, while the P + M′ cultures evolved into P-type cultures with reduced P-factor potentials. However, after 30 generations of culture, both these types of mixed cultures had similar P copy numbers, suggesting that regulation of copy number had occurred in them.

Sign in / Sign up

Export Citation Format

Share Document