Genetic damage to a fern population growing in a polluted environment: segregation and description of gametophyte mutants

1977 ◽  
Vol 55 (5) ◽  
pp. 542-548 ◽  
Author(s):  
Edward J. Klekowski Jr. ◽  
Edward L. Davis
Keyword(s):  
Maternal Effect ◽  
High Frequency ◽  
Female Parent ◽  
Chromosome Damage ◽  
Polluted Environment ◽  
Genetic Damage ◽  
Polluted River ◽  
Polluted Sites

A population of the fern Osmunda regalis growing in a polluted river was investigated genetically. Previous studies documented a high frequency of postzygotically induced genetic and chromosome damage. This paper describes two categories of gametophytic mutants which occurred in the progeny of this population. A gametophyte phenotype which exhibited a maternal effect on the sporophyte generation when it was the female parent occurred in 7.8% of the spore sample. A gametophyte phenotype which could best be characterized as a neuter calluslike mass occurred in 6.6% of the spore sample. Studies of nearby O. regalis populations in non-polluted sites failed to document the presence of such phenotypes in the spore samples.

INHERITANCE OF MUTATOR ACTIVITY IN ZEA MAYS AS ASSAYED BY SOMATIC INSTABILITY OF THE bz2-mu1 ALLELE

Genetics ◽  
1986 ◽  
Vol 114 (4) ◽  
pp. 1293-1312
Author(s):  
Virginia Walbot
Keyword(s):  
High Frequency ◽  
De Novo ◽  
Female Parent ◽  
Somatic Instability ◽  
Active Line ◽  
Anthocyanin Pathway ◽  
Mutator Activity ◽  
Activity State ◽  
Aleurone Tissue ◽  
Forward Mutation

ABSTRACT Mutator lines of maize were originally defined by their high forward mutation rate, now known to be caused by the transposition of numerous Mu elements. A high frequency of somatic instability, seen as a fine purple spotting pattern on the aleurone tissue, is characteristic of Mu-induced mutable alleles of genes of the anthocyanin pathway. Loss of such somatic instability has been correlated with the de novo, specific modification of Mu element DNA. In this report the presence or loss of somatic instability at the bz2-mu1 allele has been monitored to investigate the inheritance of the Mutator phenomenon. The active state is labile and may become weakly active (low fraction of spotted kernel progeny) or totally inactive (no spotted kernel progeny) during either outcrossing to non-Mutator lines or on self-pollination. In contrast, the inactive state is relatively permanent with rare reactivation in subsequent crosses to non-Mutator lines. Cryptic bz2-mu1 alleles in weakly active lines can be efficiently reactivated to somatic instability when crossed with an active line. However, in reciprocal crosses of active and totally inactive individuals, strong maternal effects were observed on the inactivation of a somatically unstable bz2-mu1allele and on the reactivation of cryptic bz2-mu1 alleles. In general, the activity state of the female parent determines the mutability of the progeny.

scholarly journals Phytoremediation and Agricultural Productivity – A mini review

1970 ◽  
pp. 15-19
Author(s):  
G. F. Akomolafe ◽  
K. C. Onwusiri ◽  
F. A. Adokpa
Keyword(s):  
Human Activities ◽  
Agricultural Land ◽  
Agricultural Productivity ◽  
Polluted Environment ◽  
Toxic Compounds ◽  
Green Plants ◽  
Biological Features ◽  
Polluted Sites ◽  
Crops Yield

The productivity of Agricultural land has reduced drastically particularly in highly industrialized and oil producing Countries as a result of incessant discharge of toxic compounds from many human activities into the environment. Plants are described as effective organisms for remediating polluted environment mainly due to their exceptional biological features. Some of the popular, modern and commercialized processes that have been used over the years in decontaminating polluted sites are not eco-friendly and are expensive. This is why more emphasis is laid on less-expensive and eco-friendly technique which uses green plants called phytoremediation. This review described phytoextraction, phytostabilization, rhizofiltration, phytodegradation and phytovolatilization as various techniques of phytoremediation with examples of plants that are used for this purpose. It also clearly describes healthy soil as promoter of crops yield and improving the lively hood of man and other organisms in the ecosystem.

scholarly journals Chromosome damage and early developmental arrest caused by the Rex element of Drosophila melanogaster.

Genetics ◽  
1994 ◽  
Vol 138 (2) ◽  
pp. 401-411 ◽  
Author(s):  
L G Robbins ◽  
S Pimpinelli
Keyword(s):  
Drosophila Melanogaster ◽  
Ribosomal Dna ◽  
Maternal Effect ◽  
Cell Biology ◽  
Chromosome Breakage ◽  
Chromosome Damage ◽  
Specific Chromosome ◽  
Developmental Arrest ◽  
Early Embryos ◽  
Early Developmental

Abstract Rex (Ribosomal exchange) is a genetically identified repeated element within the ribosomal DNA (rDNA) of Drosophila melanogaster. Rex has a semidominant maternal effect that promotes exchange between and within rDNA arrays in the first few embryonic mitoses. Several of Rex's genetic properties suggest that its primary effect is rDNA-specific chromosome breakage that is resolved by recombination. We report here that rDNA crossovers are only a small, surviving minority of Rex-induced events. Cytology of embryos produced by Rex-homozygous females reveals obvious chromosome damage in at least a quarter of the embryos within the first three mitotic divisions. More than half of the embryos produced by Rex females die, and the developmental arrest is among the earliest reported for any maternal-effect lethal. The striking lethal phenotype suggests that embryos with early chromosome damage could be particularly fruitful subjects for analysis of the cell biology of early embryos.

scholarly journals Single cell gel electrophoresis as a tool to assess genetic damage in Heleobia cf. australis (Mollusca: Gastropoda) as sentinel for industrial and domestic pollution in Montevideo bay (Uruguay)

2015 ◽  
Vol 63 (3) ◽  
pp. 347-354 ◽  
Author(s):  
Silvia Villar ◽  
Noelia Kandratavicius ◽  
Stefanie Martinez ◽  
Pablo Muniz
Keyword(s):  
Comet Assay ◽  
Gel Electrophoresis ◽  
Aquatic Organisms ◽  
Genetic Damage ◽  
Single Cell Gel Electrophoresis ◽  
Polluted Sites ◽  
Almost All ◽  
The Impact ◽  
Genetic Biomarker

AbstractThe knowledge of the extent of DNA damage in aquatic organisms in polluted areas is an important issue because contamination may alter their health at sublethal levels. Although molluscs have been widely used to monitor water pollution, there are no records of in vivo genotoxicity studies. Heleobia cf. australis, is distributed in almost all Uruguayan coastal ecosystems, including highly polluted sites. The comet assay is a damage genetic biomarker based on the migration of negatively charged DNA fragments produced by mutagenic agents in individual cells. Live individuals were collected in the Montevideo Bay (impacted area) and Laguna Garzón (control) to analyze the presence of mutagenic agents in the former site through comet assay. Cells from organisms of the impacted area showed significantly higher levels of genetic damage than those obtained in the control population, measured by percentage of DNA in the tail. Although preliminary, this approach supports the idea that H. cf. australis could be used as a sentinel to evaluate the presence of mutagenic agents in estuarine environments, alerting to the impact of contamination in its early stages.

scholarly journals Flamenco, a gene controlling the gypsy retrovirus of Drosophila melanogaster.

Genetics ◽  
1995 ◽  
Vol 139 (2) ◽  
pp. 697-711 ◽  
Author(s):  
N Prud'homme ◽  
M Gans ◽  
M Masson ◽  
C Terzian ◽  
A Bucheton
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Maternal Effect ◽  
High Frequency ◽  
Mutant Allele ◽  
Null Allele ◽  
Germ Line ◽  
Endogenous Retrovirus ◽  
Host Gene ◽  
Dominant Mutation

Abstract Gypsy is an endogenous retrovirus of Drosophila melanogaster. It is stable and does not transpose with detectable frequencies in most Drosophila strains. However, we have characterized unstable strains, known as MG, in which it transposes at high frequency. These stocks contain more copies of gypsy than usual stocks. Transposition results in mutations in several genes such as ovo and cut. They are stable and are due to gypsy insertions. Integrations into the ovoD1 female sterile-dominant mutation result in a null allele of the gene and occurrence of fertile females. This phenomenon, known as the ovoD1 reversion assay, can be used to quantitate gypsy activity. We have shown that the properties of MG strains result from mutation of a host gene that we called flamenco (flam). It has a strict maternal effect on gypsy mobilization: transposition occurs at high frequency only in the germ line of the progeny of females homozygous for mutations of the gene. It is located at position 65.9 (20A1-3) on the X chromosome. The mutant allele present in MG strains is essentially recessive. Flamenco seems to control the infective properties of gypsy.

scholarly journals Cytogenetic and teratological effects of mancozeb pre natal exposure on rats

1999 ◽  
Vol 42 (2) ◽  
Author(s):  
V. L. Castro ◽  
A. J. Tambasco ◽  
L. C. Paraíba ◽  
D. D. Tambasco
Keyword(s):  
Body Weight ◽  
Motor Development ◽  
Swimming Performance ◽  
Physical Development ◽  
Female Rats ◽  
Chromosome Damage ◽  
Vaginal Opening ◽  
Genetic Damage ◽  
Teratogenic Risk ◽  
Pregnant Females

Studies were conducted on the dam’s fertility and pup viability, litter physical and motor development and chromosomal analysis with female rats exposed to different concentrations of mancozeb, at initial and organogenesis periods of pregnancy. The exposure did not interfere with the pregnant females or their estrous cycle but resulted in retarded physical development, with exception of the vaginal opening and tests descent; which were in advance. The litter body weight was not affected. The examination of swimming performance indicated an initial impairment and a posterior recovery. The observed chromosome damage in dams and pups was found to enhance with the fungicide’s concentration. The results obtained led to the conclusion that even in the absence of maternal signs of toxicity, mancozeb could be related to some genetic damage and teratogenic risk to the population exposed.

Reproductive Efficiency in Reciprocal Crosses of Arachis duranensis and A. stenosperma with A. hypogaea cv. NC 61

1992 ◽  
Vol 19 (1) ◽  
pp. 46-51 ◽  
Author(s):  
Harold E. Pattee ◽  
H. Thomas Stalker
Keyword(s):  
High Frequency ◽  
Diploid Species ◽  
Female Parent ◽  
Reproductive Efficiency ◽  
Reproductive Barriers ◽  
Genetic Incompatibility ◽  
Parental Effect ◽  
Reciprocal Crosses ◽  
Arachis Duranensis ◽  
Wild Diploid Species

Abstract The wild species germplasm resources of Arachis are potentially valuable for improving disease and insect resistance in A. hypogaea L. Improving cultivars through interspecific hybridization is restricted because of reproductive barriers and/or genetic incompatibility with many Arachis spp. A description of reproductive efficiency in reciprocal crosses between wild and cultivated Arachis species is needed to clarify potentials for germplasm utilization. This study documents reproductive efficiency using the diploid species A. duranensis (K 7988) and A. stenosperma (HLK 410) in reciprocal crosses with A. hypogaea cv. NC 6. A significant parental effect was observed among crosses and NC 6 was more successful when used as the female parent. Differences in total reproductive efficiency were not observed between the two wild diploid species. However, when A. duranensis was used as a female parent embryos aborted at a high frequency. In contrast, the reduced efficiency observed with A. stenosperma was due to lower fertilization. As attempts are made to utilize the genetic resources of Arachis, different approaches will be needed to overcome reproductive barriers which restrict introgression of potentially desirable traits.

The Microstructure of Steatite (Protoenstatite)

1985 ◽  
Vol 43 ◽  
pp. 236-237
Author(s):  
W. E. Lee ◽  
A. H. Heuer
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Magnesium Silicate ◽  
Beam Current ◽  
Glassy Matrix ◽  
Angle Of Incidence ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Argon Ions ◽  
High Temperature Polymorph

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

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