A case of spontaneous chromosome breakage at a specific locus occurring at meiosis

1966 ◽  
Vol 14 (6) ◽  
pp. 1027 ◽  
Author(s):  
MJD White
Keyword(s):  
Natural Populations ◽  
Chromosome Breakage ◽  
Acentric Fragment ◽  
Single Male ◽  
Causal Explanations ◽  
Male Individual ◽  
Large Pair ◽  
Spontaneous Chromosome ◽  
Specific Locus ◽  
The One

The undescribed species of grasshopper PW21 (Orthoptera: Eumastacidae: Morabinae) from northern Australia has been found to exhibit three different karyotypes in its natural populations. Two of these have 2nB = 13, the third has 2nB = 15. Males are invariably XO, but the X may be either acrocentric or metacentric. The relation between the 13-chromosome karyotypes and the 15-chromosome one is complex. In a single male individual of the 15-chromosome population (out of four examined cytologically) one of the large pair of metacentric chromosomes regularly undergoes fragmentation at a locus close to the centromere just before first metaphase. The acentric fragment is caught up in the spindle but frequently travels to the "wrong" pole at first anaphase. Possible causal explanations of this phenomenon are discussed. These include the one-locus hypothesis ("suicide" of a chromosome) and various two-locus hypotheses ("murder" of one chromosome by another).

scholarly journals Spontaneous chromosome breakage in natural populations of Najas marina

Hereditas ◽  
2009 ◽  
Vol 88 (2) ◽  
pp. 279-283 ◽  
Author(s):  
Yrjö Viinikka ◽  
Maija Kotimäki ◽  
Kirsi Litmanen
Keyword(s):  
Natural Populations ◽  
Chromosome Breakage ◽  
Najas Marina ◽  
Spontaneous Chromosome

Riyadh Chromosome Breakage Syndrome: Mental Retardation With Depigmentation of the Skin and Hair

1992 ◽  
Vol 7 (1_suppl) ◽  
pp. S79-S82 ◽  
Author(s):  
Pinar T. Ozand ◽  
Manjula Waghray ◽  
Jay D. Cook ◽  
Kirtikant Sheth ◽  
Generoso G. Gascon
Keyword(s):  
Mental Retardation ◽  
Sister Chromatid ◽  
Chromosome Breakage ◽  
Hair Color ◽  
Γ Irradiation ◽  
Exchange Frequency ◽  
Chromosome Breaks ◽  
Chromosome Breakage Syndrome ◽  
Sister Chromatid Exchange Frequency ◽  
Spontaneous Chromosome

A 20-month-old infant with "silvery-blond" hair color, widespread confettilike depigmentation of the skin, and mental retardation was found to have, in lymphocytes and fibroblast cultures, increased spontaneous chromosome breaks and breaks induced by both mitomycin and γ-irradiation. The sister chromatid exchange frequency was normal. This child probably represents a new chromosome breakage syndrome. (J Child Neurol 1992;7(Suppl):S79-S82.)

scholarly journals Assessment of the susceptibility status of Aedes aegypti (Diptera: Culicidae) populations to pyriproxyfen and malathion in a nation-wide monitoring of insecticide resistance performed in Brazil from 2017 to 2018

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Kauara Brito Campos ◽  
Ademir Jesus Martins ◽  
Cynara de Melo Rodovalho ◽  
Diogo Fernandes Bellinato ◽  
Luciana dos Santos Dias ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Mosquito Control ◽  
Natural Populations ◽  
Adult Emergence ◽  
World Health ◽  
Two Generations ◽  
Wide Scale ◽  
Susceptibility Tests ◽  
The One ◽  
Health Organization

Abstract Background Chemical mosquito control using malathion has been applied in Brazil since 1985. To obtain chemical control effectiveness, vector susceptibility insecticide monitoring is required. This study aimed to describe bioassay standardizations and determine the susceptibility profile of Ae. aegypti populations to malathion and pyriproxyfen, used on a national scale in Brazil between 2017 and 2018, and discuss the observed impacts in arbovirus control. Methods The diagnostic-doses (DD) of pyriproxyfen and malathion were determined as the double of adult emergence inhibition (EI) and lethal doses for 99% of the Rockefeller reference strain, respectively. To monitor natural populations, sampling was performed in 132 Brazilian cities, using egg traps. Colonies were raised in the laboratory for one or two generations (F1 or F2) and submitted to susceptibility tests, where larvae were exposed to the pyriproxyfen DD (0.03 µg/l) and adults, to the malathion DD determined in the present study (20 µg), in addition to the one established by the World Health Organization (WHO) DD (50 µg) in a bottle assay. Dose-response (DR) bioassays with pyriproxyfen were performed on populations that did not achieve 98% EI in the DD assays. Results Susceptibility alterations to pyriproxyfen were recorded in six (4.5%) Ae. aegypti populations from the states of Bahia and Ceará, with Resistance Ratios (RR95) ranging from 1.51 to 3.58. Concerning malathion, 73 (55.3%) populations distributed throughout the country were resistant when exposed to the local DD 20 µg/bottle. On the other hand, no population was resistant, and only 10 (7.6%) populations in eight states were considered as exhibiting decreased susceptibility (mortality ratios between 90 and 98%) when exposed to the WHO DD (50 µg/bottle). Conclusions The feasibility of conducting an insecticide resistance monitoring action on a nation-wide scale was confirmed herein, employing standardized and strongly coordinated sampling methods and laboratory bioassays. Brazilian Ae. aegypti populations exhibiting decreased susceptibility to pyriproxyfen were identified. The local DD for malathion was more sensitive than the WHO DD for early decreased susceptibility detection.

Spontaneous chromosome breakage in hybrid endosperms

Chromosoma ◽  
1956 ◽  
Vol 8 (1) ◽  
pp. 317-340 ◽  
Author(s):  
Alfred Rutishauser ◽  
L. F. La Cour
Keyword(s):  
Chromosome Breakage ◽  
Spontaneous Chromosome

scholarly journals The costs of being male: are there sex-specific effects of uniparental mitochondrial inheritance?

2014 ◽  
Vol 369 (1646) ◽  
pp. 20130440 ◽  
Author(s):  
Madeleine Beekman ◽  
Damian K. Dowling ◽  
Duur K. Aanen
Keyword(s):  
Maternal Inheritance ◽  
Phenotypic Expression ◽  
Natural Populations ◽  
Mtdna Mutations ◽  
Specific Effects ◽  
Mtdna Sequence ◽  
Multiple Copies ◽  
The One ◽  
Mtdna Variants ◽  
Male Expression

Eukaryotic cells typically contain numerous mitochondria, each with multiple copies of their own genome, the mtDNA. Uniparental transmission of mitochondria, usually via the mother, prevents the mixing of mtDNA from different individuals. While on the one hand, this should resolve the potential for selection for fast-replicating mtDNA variants that reduce organismal fitness, maternal inheritance will, in theory, come with another set of problems that are specifically relevant to males. Maternal inheritance implies that the mitochondrial genome is never transmitted through males, and thus selection can target only the mtDNA sequence when carried by females. A consequence is that mtDNA mutations that confer male-biased phenotypic expression will be prone to evade selection, and accumulate. Here, we review the evidence from the ecological, evolutionary and medical literature for male specificity of mtDNA mutations affecting fertility, health and ageing. While such effects have been discovered experimentally in the laboratory, their relevance to natural populations—including the human population—remains unclear. We suggest that the existence of male expression-biased mtDNA mutations is likely to be a broad phenomenon, but that these mutations remain cryptic owing to the presence of counter-adapted nuclear compensatory modifier mutations, which offset their deleterious effects.

Fragile sites in chromosomes: possible model for the study of spontaneous chromosome breakage

Science ◽  
1983 ◽  
Vol 220 (4592) ◽  
pp. 69-70 ◽  
Author(s):  
P. Jacky ◽  
B Beek ◽  
G. Sutherland
Keyword(s):  
Chromosome Breakage ◽  
Fragile Sites ◽  
Spontaneous Chromosome

Genotoxic Effect of Inhaled Ambient Particulate Matter

2012 ◽  
Vol 18 (S5) ◽  
pp. 25-26
Author(s):  
A. S. Boa-Alma ◽  
G. Ramalhinho ◽  
D. Dias ◽  
M. L. Mathias ◽  
P. A Carvalho ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Micronucleus Test ◽  
Natural Populations ◽  
Micronucleus Assay ◽  
Chromosome Breakage ◽  
Epidemiological Studies ◽  
Ambient Particulate Matter ◽  
Good Tool ◽  
Short And Long Term

In recent years great importance has been given to the adverse effects of particulate matter (PM) in health, and several epidemiological studies correlating the airborne particles with pulmonary injury have been carried out. The adverse effect of short- and long-term expositions to PM can, indeed, cause a variety of effects, from minor effects on the respiratory system to serious oncogenic effects that can lead to precocious death and are considered one of the top environmental public health concerns. Some cytogenetic techniques, as micronucleus assay, allow to detect chromosome breakage and loss by measuring the formation of micronuclei and proved to be a good tool in the evaluation of genotoxic damage induced by PM. Thus genotoxic effects can be evaluated by micronucleus test in order to identify a gradient of potential exposure and to assess environmental monitoring. However, cross investigations involving biomarkers of genotoxicity and electron microscopy PM-induced tracheal and lung damages in natural populations are not common.

scholarly journals Kognition og kultur: Boyer versus Wittgenstein

2005 ◽  
Author(s):  
Lars Albinus
Keyword(s):  
Cognitive Science ◽  
Ludwig Wittgenstein ◽  
Scientific Explanation ◽  
Social Reality ◽  
The Other ◽  
Human Language ◽  
Cognitive Capacities ◽  
Causal Explanations ◽  
The One ◽  
Psychological Activity

Cognitive science typically insists on procuring causal explanations for psychological activity on a pre-cultural level. In this article it is claimed that the price for doing so may be too high and that it escapes philosophical justification in the first place. A more specific criticism is directed against what thus seems to be an ignorant notion of culture in Religion Explained by Pascal Boyer. Drawing on Ludwig Wittgenstein and Meredith Williams, who is a lucid reader of his work, the psychological attempt to explain feelings and memories on the grounds of innate cognitive capacities is found to be profoundly misleading. The question is how to understand, on the one hand, human language and, on the other, the possible scope of scientific explanation. Arguing for an irreducible level of social reality, this article focuses on the limitations of cognitive science, while also bringing out the aporia caused by an epistemological trap of self-referentiality.

scholarly journals Seasonal Variation in the Dietary Preferences of the Montane Vole, Microtus Montanus

1995 ◽  
Vol 19 ◽  
pp. 76-77
Author(s):  
Aeltia Pinter ◽  
Norman Negus ◽  
Patricia Berger
Keyword(s):  
Population Dynamics ◽  
Seasonal Variation ◽  
Plant Species ◽  
Food Selection ◽  
Natural Populations ◽  
Food Preferences ◽  
Plant Resources ◽  
Microtus Montanus ◽  
Dietary Preferences ◽  
The One

Seasonal variation in food selection has been documented in several species on voles (Rothstein and Tamarin 1977, Cole and Batzli 1979 Goldberg et al. 1980) with considerable implications for winter survival and population dynamics. In Microtus Montanus a similar link may exist between growth, maturation, longevity, and population dynamics on the one hand and dietary composition on the other (e.g., Pinter and Negus 1965, Berger et al. 1981, Pinter 1988, Berger et al. 1992, Negus, Berger and Pinter 1992). Consequently, we undertook a study to investigate, in detail, the utilization of plant resources by the montane vole, Microtus montanus. The objectives of this project are twofold: (1) to identify the plant species that constitute the diet in natural populations of M. montanus and (2) to determine seasonal food preferences in relation to the availability of plant species and to the age, sex and cohorts of the montane vole.

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