scholarly journals Laboratory generation of new Artemia parthenogenetic lineages through contagious parthenogenesis

2014 ◽  
Author(s):  
Marta Maccari ◽  
Francisco Amat ◽  
Francisco Hontoria ◽  
Africa Gómez
Keyword(s):  
Sex Ratio ◽  
Brine Shrimp ◽  
Reproductive Mode ◽  
Natural Environments ◽  
F1 Hybrid ◽  
Genetic Mechanisms ◽  
Rare Males ◽  
Males And Females ◽  
Evolutionary Role

Contagious parthenogenesis – a process involving rare functional males produced by a parthenogenetic lineage, which mate with coexisting sexual females resulting in fertile parthenogenetic offspring – is one of the most striking mechanisms responsible for the generation of new parthenogenetic lineages. Populations of the parthenogenetic diploid brine shrimp Artemia produce fully functional males in low proportions. The evolutionary role of these so-called Artemia rare males is, however, unknown. Here we investigate whether new parthenogenetic clones could be obtained in the laboratory through contagious origin. We assessed the survival and sex ratio of the hybrid ovoviviparous offspring from previous crosses between rare males and females from all Asiatic sexual species, carried out cross-mating experiments between F1 hybrid individuals to assess their fertility, and estimated the viability and the reproductive mode of the resulting F2 offspring. Molecular analysis confirmed the parentage of hybrid parthenogenetic F2. Our study documents the first synthesis of parthenogenetic lineages through contagious parthenogenesis in Artemia. We discuss the possible genetic mechanisms responsible for parthenogenesis and the likelihood of contagious parthenogenesis in natural environments.

scholarly journals Laboratory generation of new Artemia parthenogenetic lineages through contagious parthenogenesis

2014 ◽  
Author(s):  
Marta Maccari ◽  
Francisco Amat ◽  
Francisco Hontoria ◽  
Africa Gómez
Keyword(s):  
Sex Ratio ◽  
Brine Shrimp ◽  
Reproductive Mode ◽  
Natural Environments ◽  
F1 Hybrid ◽  
Genetic Mechanisms ◽  
Rare Males ◽  
Males And Females ◽  
Evolutionary Role

Contagious parthenogenesis – a process involving rare functional males produced by a parthenogenetic lineage, which mate with coexisting sexual females resulting in fertile parthenogenetic offspring – is one of the most striking mechanisms responsible for the generation of new parthenogenetic lineages. Populations of the parthenogenetic diploid brine shrimp Artemia produce fully functional males in low proportions. The evolutionary role of these so-called Artemia rare males is, however, unknown. Here we investigate whether new parthenogenetic clones could be obtained in the laboratory through contagious origin. We assessed the survival and sex ratio of the hybrid ovoviviparous offspring from previous crosses between rare males and females from all Asiatic sexual species, carried out cross-mating experiments between F1 hybrid individuals to assess their fertility, and estimated the viability and the reproductive mode of the resulting F2 offspring. Molecular analysis confirmed the parentage of hybrid parthenogenetic F2. Our study documents the first synthesis of parthenogenetic lineages through contagious parthenogenesis in Artemia. We discuss the possible genetic mechanisms responsible for parthenogenesis and the likelihood of contagious parthenogenesis in natural environments.

scholarly journals Are hermaphrodites better adapted to the colonization process in trioecious populations of Salix myrsinifolia?

2015 ◽  
Vol 84 (2) ◽  
pp. 167-175 ◽  
Author(s):  
Paweł Mirski ◽  
Emilia Brzosko
Keyword(s):  
Sex Ratio ◽  
Reproductive Number ◽  
Vegetative Traits ◽  
Average Share ◽  
Northeastern Poland ◽  
Colonization Process ◽  
Males And Females ◽  
Salix Myrsinifolia ◽  
Two Populations

In trioecious plant populations, the role of hermaphroditism is often uncertain. We investigated the advantages of hermaphroditism in the dioecious shrub <em>Salix myrsinifolia</em>. The sex ratio of 30 <em>S. myrsinifolia</em> populations in northeastern Poland (secondary range) and Lithuania (primary range) was investigated in 2010–2011. Measures of reproductive (number of catkins, number of flowers in catkins) and vegetative traits (height, diameter, number of shoots, vitality) were taken and compared among sexual morphs. In two populations, measurements collected 14 years prior on marked individuals were used to determine the rate of changes in height, crown diameter and survivorship rates. We found trioecy mostly in the secondary part of the range with an average share of hermaphrodites reaching 21% in the trioecious populations. The sex ratio varied between populations, but tended mostly towards female domination. Several traits differed significantly among sexes. The characteristics of hermaphrodites were often intermediate between males and females and provided no evidence for the higher competitive abilities of hermaphrodites. We concluded that the possible gain of hermaphroditism in the colonization process is restricted to reproduction. We consider hermaphroditism in <em>S. myrsinifolia</em> as an equilibrium between the allocation of resources for growth and reproduction in unstable conditions on the margins of the range.

scholarly journals The case of the midwife toad revisited

2017 ◽  
Vol 86 (4) ◽  
pp. 261-272 ◽  
Author(s):  
Jacques J. M. van Alphen ◽  
Jan W. Arntzen
Keyword(s):  
Natural Selection ◽  
Egg Size ◽  
Life History Traits ◽  
Reproductive Mode ◽  
Lamarckian Evolution ◽  
Gradual Development ◽  
Genetic Mechanisms ◽  
Midwife Toad ◽  
Existing Data

In a recent paper it was suggested that results published by Kammerer (1911) on the midwife toad could be explained by epigenetics (Vargas et al., 2016). We show that data thought to be fitting are based on untested assumptions about the underlying genetic mechanisms. We cite recent studies on the genetics of life history traits, in particular egg-size and number, to show that these assumptions are not realistic. We review aspects of Kammerer’s experimental results on the midwife toad for which there are no plausible mechanisms, i.e. toads switching from land-breeding to water-breeding in response to an increase in temperature, eggs becoming resistant to moulds within a few generations, the gradual development of nuptial pads, heterochronous changes in the development of water-born larvae, and conclude that Kammerer cannot have obtained the results he claims. We argue that natural selection would not have favoured a change in reproductive mode and the loss of parental care and that an epigenetic master switch, affecting many different traits simultaneously, would have either eroded during more than 15 million years of land-breeding and/or would have disappeared by natural selection against it. Finally, we show that Kammerer's data are remarkably close to the invoked Mendelian ratio and too good to be genuine. We conclude that Kammerer’s data are fictitious and that Vargas et al. (2016) have used non-existing data in search of support for a role of epigenetics in neo-Lamarckian evolution.

Gender Diversity in Computing: An Environmental Perspective

10.28945/3248 ◽  
2008 ◽  
Author(s):  
Cecille Marsh
Keyword(s):  
Gender Diversity ◽  
Household Head ◽  
Female Students ◽  
Political Factors ◽  
Female Household Head ◽  
Dominant Female ◽  
Computer Confidence ◽  
Males And Females ◽  
Research Questions

Previous research conducted by the author investigated the socio-political backgrounds of two groups of female students studying computer-related university programmes. They came from distinctly different backgrounds and were enrolled at two institutions with very different legacies. The author found that socio-political factors, in particular the role of a dominant female household head and aggressive governmental affirmative action, had a significant effect on the girls’ levels of confidence and subsequently on their decision to study computer-related courses. Based on this insight, the researcher undertook to look further into gender diversity with respect to self-perceived general computer confidence and self-perceived ability to program a computer. A sample of both female and male Information T echnology students from very similar disadvantaged socio-economic backgrounds was surveyed. The sample of 204 students was drawn from all three years of the National Diploma in Information Technology. The author considered the following research questions: (i) Do males and females studying computer-related courses have differing computer selfefficacy levels? (ii) Do males and females studying computer programming have differing attitudes towards their ability to program? (iii) Do males and females differ in their attitudes towards the programming learning environment?

Evolutionary role of the community pharmacist A review

2017 ◽  
Vol 4 (4) ◽  
pp. 136-139
Author(s):  
Firdous Fatima ◽  
◽  
Bushra Ali Sherazi
Keyword(s):  
Community Pharmacist ◽  
Evolutionary Role

Selenium Role in Reproduction, Pregnant/Postpartum Women and Neonates: A Current Study

2020 ◽  
Vol 17 (1) ◽  
pp. 28-37
Author(s):  
Tabinda Sattar
Keyword(s):  
Infant Development ◽  
Selenium Deficiency ◽  
Human Reproduction ◽  
Postpartum Women ◽  
Female Reproduction ◽  
Pregnancy And Lactation ◽  
Males And Females ◽  
One Year ◽  
Selenium Supplements

Background: Selenium is a micronutrient, although required in low amounts, its importance in male and female reproduction is well known. Objectives: The core purpose of this study is to evaluate the role of selenium in human reproduction, during pregnancy/ lactation in women and newborns. The review explains side by side the sources of selenium, required amounts of selenium in humans and during pregnancy or lactation. Methods: Selenium deficiency is a major cause of male infertility. Similarly, selenium deficiency, both in pregnant and postpartum women, would greatly affect the health of the newborn baby in all respects. The effect of maternal selenium upon the fetus and the neonates even one year after birth has been explained with some recent examples. Results: The study elaborates the fact that the selenium deficiency in pregnancy and lactation is common due to fetal/infant development, so selenium supplements must be provided in order to overcome these deficiency symptoms. Conclusions: The better reproductive health in humans is possible due to the sufficient amounts of selenium present both in males and females as well.

scholarly journals Genetic Studies of mei-P26 Reveal a Link Between the Processes That Control Germ Cell Proliferation in Both Sexes and Those That Control Meiotic Exchange in Drosophila

Genetics ◽  
2000 ◽  
Vol 155 (4) ◽  
pp. 1757-1772 ◽  
Author(s):  
Scott L Page ◽  
Kim S McKim ◽  
Benjamin Deneen ◽  
Tajia L Van Hook ◽  
R Scott Hawley
Keyword(s):  
Meiotic Recombination ◽  
Double Mutant ◽  
P Element ◽  
Genetic Studies ◽  
Germline Differentiation ◽  
Males And Females ◽  
Bag Of Marbles ◽  
Differentiation And Proliferation

Abstract We present the cloning and characterization of mei-P26, a novel P-element-induced exchange-defective female meiotic mutant in Drosophila melanogaster. Meiotic exchange in females homozygous for mei-P261 is reduced in a polar fashion, such that distal chromosomal regions are the most severely affected. Additional alleles generated by duplication of the P element reveal that mei-P26 is also necessary for germline differentiation in both females and males. To further assess the role of mei-P26 in germline differentiation, we tested double mutant combinations of mei-P26 and bag-of-marbles (bam), a gene necessary for the control of germline differentiation and proliferation in both sexes. A null mutation at the bam locus was found to act as a dominant enhancer of mei-P26 in both males and females. Interestingly, meiotic exchange in mei-P261; bamΔ86/+ females is also severely decreased in comparison to mei-P261 homozygotes, indicating that bam affects the meiotic phenotype as well. These data suggest that the pathways controlling germline differentiation and meiotic exchange are related and that factors involved in the mitotic divisions of the germline may regulate meiotic recombination.

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