scholarly journals Effect of parental RNA interference of a transformer-2 homologue on female reproduction and offspring sex determination in Asian citrus psyllid

2017 ◽  
Vol 43 (1) ◽  
pp. 42-50 ◽  
Author(s):  
Xiudao Yu ◽  
Nabil Killiny
Keyword(s):  
Rna Interference ◽  
Sex Determination ◽  
Asian Citrus Psyllid ◽  
Female Reproduction ◽  
Offspring Sex

scholarly journals RNA Interference Screening Reveals Redox Processes to be Most Responsive to Low dsRNA Doses in Asian Citrus Psyllid

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
John E. Ramos ◽  
Robert G. Shatters ◽  
Charles A. Powell ◽  
Dov Borovsky ◽  
Ritesh Jain ◽  
...  
Keyword(s):  
Rna Interference ◽  
Asian Citrus Psyllid ◽  
Redox Processes

scholarly journals Genetic evidence for co-occurrence of chromosomal and thermal sex-determining systems in a lizard

2007 ◽  
Vol 4 (2) ◽  
pp. 176-178 ◽  
Author(s):  
Rajkumar S Radder ◽  
Alexander E Quinn ◽  
Arthur Georges ◽  
Stephen D Sarre ◽  
Richard Shine
Keyword(s):  
Sex Determination ◽  
Female Offspring ◽  
Temperature Dependent ◽  
Sex Marker ◽  
Heteromorphic Sex Chromosomes ◽  
Offspring Sex ◽  
Current Classification ◽  
Genotypic Sex Determination ◽  
Incubation Temperatures ◽  
Bassiana Duperreyi

An individual's sex depends upon its genes (genotypic sex determination or GSD) in birds and mammals, but reptiles are more complex: some species have GSD whereas in others, nest temperatures determine offspring sex (temperature-dependent sex determination). Previous studies suggested that montane scincid lizards ( Bassiana duperreyi , Scincidae) possess both of these systems simultaneously: offspring sex is determined by heteromorphic sex chromosomes (XX–XY system) in most natural nests, but sex ratio shifts suggest that temperatures override chromosomal sex in cool nests to generate phenotypically male offspring even from XX eggs. We now provide direct evidence that incubation temperatures can sex-reverse genotypically female offspring, using a DNA sex marker. Application of exogenous hormone to eggs also can sex-reverse offspring (oestradiol application produces XY as well as XX females). In conjunction with recent work on a distantly related lizard taxon, our study challenges the notion of a fundamental dichotomy between genetic and thermally determined sex determination, and hence the validity of current classification schemes for sex-determining systems in reptiles.

scholarly journals Does sex-ratio selection influence nest-site choice in a reptile with temperature-dependent sex determination?

2013 ◽  
Vol 280 (1772) ◽  
pp. 20132460 ◽  
Author(s):  
Timothy S. Mitchell ◽  
Jessica A. Maciel ◽  
Fredric J. Janzen
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
Nest Site ◽  
Sex Ratios ◽  
Temperature Dependent ◽  
Dioecious Species ◽  
Offspring Sex Ratio ◽  
Nest Sites ◽  
Offspring Sex ◽  
Nest Site Choice

Evolutionary theory predicts that dioecious species should produce a balanced primary sex ratio maintained by frequency-dependent selection. Organisms with environmental sex determination, however, are vulnerable to maladaptive sex ratios, because environmental conditions vary spatio-temporally. For reptiles with temperature-dependent sex determination, nest-site choice is a behavioural maternal effect that could respond to sex-ratio selection, as mothers could adjust offspring sex ratios by choosing nest sites that will have particular thermal properties. This theoretical prediction has generated decades of empirical research, yet convincing evidence that sex-ratio selection is influencing nesting behaviours remains absent. Here, we provide the first experimental evidence from nature that sex-ratio selection, rather than only viability selection, is probably an important component of nest-site choice in a reptile with temperature-dependent sex determination. We compare painted turtle ( Chrysemys picta ) neonates from maternally selected nest sites with those from randomly selected nest sites, observing no substantive difference in hatching success or survival, but finding a profound difference in offspring sex ratio in the direction expected based on historical records. Additionally, we leverage long-term data to reconstruct our sex ratio results had the experiment been repeated in multiple years. As predicted by theory, our results suggest that sex-ratio selection has shaped nesting behaviour in ways likely to enhance maternal fitness.

scholarly journals Conservation of sex-linked markers among conspecific populations of a viviparous skink, Niveoscincus ocellatus, exhibiting genetic and temperature dependent sex determination

2018 ◽  
Author(s):  
Peta Hill ◽  
Christopher P. Burridge ◽  
Tariq Ezaz ◽  
Erik Wapstra
Keyword(s):  
Linkage Disequilibrium ◽  
Sex Ratio ◽  
Sex Determination ◽  
Temperature Dependent ◽  
Offspring Sex Ratio ◽  
Evolutionary Transitions ◽  
Offspring Sex ◽  
Determination System ◽  
Sex Determination System ◽  
Male Heterogamety

AbstractSex determination systems are exceptionally diverse and have undergone multiple and independent evolutionary transitions among species, particularly reptiles. However, the mechanisms underlying these transitions have not been established. Here we tested for differences in sex-linked markers in the only known reptile that is polymorphic for sex determination system, the spotted snow skink, Niveoscincus ocellatus, to quantify the genomic differences that have accompanied this transition. In a highland population, sex is determined genetically, whilst in a lowland population, offspring sex ratio is influenced by temperature. We found a similar number of sex-linked loci in each population, including shared loci, with genotypes consistent with male heterogamety (XY). However, population-specific linkage disequilibrium suggests greater divergence of sex chromosomes in the highland population. Our results suggest that transitions between sex determination systems (GSD and TSD-like systems) can be facilitated by subtle genetic differences.

RNA interference of carboxyesterases causes nymph mortality in the Asian citrus psyllid,Diaphorina citri

2017 ◽  
Vol 94 (3) ◽  
pp. e21377 ◽  
Author(s):  
Abdelaziz Kishk ◽  
Helmy A. I. Anber ◽  
Tsamoh K. AbdEl-Raof ◽  
AbdEl-Hakeem D. El-Sherbeni ◽  
Sobhy Hamed ◽  
...  
Keyword(s):  
Rna Interference ◽  
Asian Citrus Psyllid ◽  
Diaphorina Citri

The evolution of genomic imprinting

Development ◽  
1990 ◽  
Vol 108 (Supplement) ◽  
pp. 47-53
Author(s):  
H. Sharat Chandra ◽  
Vidyanand Nanjundiah
Keyword(s):  
Sex Determination ◽  
Genomic Imprinting ◽  
Potential Role ◽  
Fragile X ◽  
Chromosome Elimination ◽  
Regulatory Sequences ◽  
Maternal Control ◽  
Fitness Effects ◽  
Gene Copies ◽  
Offspring Sex

We explore three possible pathways for the evolution of genomic imprinting. (1) Imprinting may be advantageous in itself when imprinted and unimprinted alleles of a locus confer different phenotypes. If a segment of DNA is imprinted in the gametes of one sex but not in those of the other, it might lead to effects correlated with sexual dimorphism. More fundamentally, in certain organisms, sex determination might have evolved because of imprinting. When imprinting leads to chromosome elimination or inactivation and occurs in some embryos but not in others, two classes of embryos, differing in the number of functional gene copies, would result. A model for sex determination based on inequality in the actual or effective copy-number of particular noncoding, regulatory sequences of DNA has been proposed (Chandra, Proc. natn. Acad. Sci. U.S.A. 82. 1165–1169 and 6947–6949, 1985). Maternal control of offspring sex is another possible consequence of imprinting; this would indicate a potential role for imprinting in sex ratio evolution. (2) Genes responsible for imprinting may have pleiotropic effects and they may have been selected for reasons other than their imprinting ability. Lack of evidence precludes further consideration of this possibility. (3) Imprinting could have co-evolved with other traits. For instance, gamete-specific imprinting could lead to a lowered fitness of androgenetic or gynogenetic diploids relative to the fitness of ‘normal’ diploids. This in turn would reinforce the evolution of anisogamy. The reversibility of imprinting raises the possibility of occasional incomplete or improper erasure. If the site of imprinting is the egg – as appears to be the case with the human X (Chandra and Brown, Nature 253. 165–168, 1975) – either improper imprinting or improper erasure could lead to unusual patterns of inheritance (as in the fragile-X syndrome) or fitness effects skipping generations.

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