scholarly journals An Extraordinary Sex Determination Mechanism in a Book Louse

Genetics ◽  
2017 ◽  
Vol 206 (2) ◽  
pp. 751-753 ◽  
Author(s):  
Leo W. Beukeboom
Keyword(s):  
Sex Determination ◽  
Determination Mechanism

Key aspects of the primary sex determination mechanism are conserved across the genus Drosophila

Development ◽  
1998 ◽  
Vol 125 (16) ◽  
pp. 3259-3268 ◽  
Author(s):  
J.W. Erickson ◽  
T.W. Cline
Keyword(s):  
Sex Determination ◽  
Rapid Onset ◽  
Amino Acid Identity ◽  
Bzip Transcription Factor ◽  
Regulatory Sequence ◽  
Tightly Coupled ◽  
Pole Cells ◽  
High Level ◽  
Key Aspects ◽  
Determination Mechanism

In D. melanogaster, a set of ‘X:A numerator genes’, which includes sisterlessA (sisA), determines sex by controlling the transcription of Sex-lethal (Sxl). We characterized sisA from D. pseudoobscura and D. virilis and studied the timing of sisA and Sxl expression with single cell-cycle resolution in D. virilis, both to guide structure-function studies of sisA and to help understand sex determination evolution. We found that D. virilis sisA shares 58% amino acid identity with its melanogaster ortholog. The identities confirm sisA as an atypical bZIP transcription factor. Although virilis sisA can substitute for melanogaster sisA, the protein is not fully functional in a heterologous context. The putative sisA regulatory sequence CAGGTAG is a potential ‘numerator box,’ since it is shared with the other strong X:A numerator gene, sisB, and its target, SxlPe. Temporal and spatial features of sisA and SxlPe expression are strikingly conserved, including rapid onset and cessation of transcription in somatic nuclei, early cessation of sisA transcription in budding pole cells and persistent high-level sisA expression in yolk nuclei. Expression of sisA and Sxl is as tightly coupled in virilis as it is in melanogaster. Taken together, these data indicate that the same primary sex determination mechanism exists throughout the genus Drosophila.

Cross-sexual Transfer

2003 ◽  
Author(s):  
Mary Jane West-Eberhard
Keyword(s):  
Sex Determination ◽  
Sexually Dimorphic ◽  
Male And Female ◽  
Alternative Phenotypes ◽  
Opposite Sex ◽  
Critical Age ◽  
Sexual Traits ◽  
Discrete Traits ◽  
Dimorphic Species ◽  
Determination Mechanism

Distinctive male and female traits are perhaps the most familiar of all divergent specializations within species. In cross-sexual transfer, discrete traits that are expressed exclusively in one sex in an ancestral species appear in the opposite sex of descendants. An example is the expression of brood care by males in a lineage where ancestral females are the exclusive caretakers of the young, as in some voles (Thomas and Birney, 1979). Despite the prominence of sexual dimorphism and sex reversals in nature, and an early explicit treatment by Darwin, discussed in the next section, cross-sexual transfer is not often recognized as a major factor in the evolution of novelty (but see, on animals, Mayr, 1963, pp. 435-439; Mayr, 1970, p. 254; on plants, Iltis, 1983). When more widely investigated, cross-sexual transfer may prove to rival heterochrony and duplication as an important source of novelties in sexually dimorphic lineages. For this reason, I devote more attention here to cross-sexual transfer than to these other, well-established general patterns of change. The male and female of a sexually dimorphic species may be so different that it is easy to forget that each individual carries most or all of the genes necessary to produce the phenotype of the opposite sex. Sex determination, like caste determination and other switches between alternative phenotypes, depends on only a few genetic loci or, in many species, environmental factors (Bull, 1983). There is considerable flexibility in sex determination and facultative reversal in some taxa. Among fish, for example, there is even a species wherein sex is determined by juvenile size at a critical age (Francis and Barlow, 1993). The sex determination mechanism, whatever its nature, leads to a series of sex-limited responses, often coordinated by hormones and not necessarily all occurring at once. A distinguishing aspect of sexually dimorphic traits in adults is that there is often a close homology between the secondary sexual traits that are differently modified in the two sexes.

scholarly journals Ⅰ-3. Sex Determination Mechanism in Seriola Fishes

2019 ◽  
Vol 85 (2) ◽  
pp. 188-188
Author(s):  
TAKASHI KOYAMA ◽  
MASATOSHI NAKAMOTO ◽  
KAGAYAKI MORISHIMA ◽  
TAKEFUMI YAMASHITA ◽  
NAOKI MIZUNO ◽  
...  
Keyword(s):  
Sex Determination ◽  
Determination Mechanism

scholarly journals Identification of Sex-Specific Markers Through 2b-RAD Sequencing in the Sea Urchin (Mesocentrotus nudus)

2021 ◽  
Vol 12 ◽  
Author(s):  
Zhouping Cui ◽  
Jian Zhang ◽  
Zhihui Sun ◽  
Bingzheng Liu ◽  
Chong Zhao ◽  
...  
Keyword(s):  
Sex Determination ◽  
Sea Urchin ◽  
Sex Differentiation ◽  
Pcr Amplification ◽  
Open Reading Frames ◽  
Genome Survey ◽  
A Genome ◽  
Mesocentrotus Nudus ◽  
Female Specific ◽  
Determination Mechanism

Sex-specific markers play an important role in revealing sex-determination mechanism. Sea urchin (Mesocentrotus nudus) is an economically important mariculture species in several Asian countries and its gonads are the sole edible parts for people. However, growth rate and immunocompetence differ by sex in this species, sex-specific markers have not been identified, and the sex-determination mechanism of sea urchin remains undetermined. In this study, type IIB endonuclease restriction-site associated DNA sequencing (2b-RAD-seq) and a genome survey of M. nudus were performed, and three female-specific markers and three female heterogametic single nucleotide polymorphism (SNP) loci were identified. We validated these sex-specific markers via PCR amplification in a large number of individuals, including wild and artificially bred populations. Several open reading frames (ORFs) were predicted, although there are no potential genes known for sex determination and sex differentiation within the scaffold in which the sex-specific markers are located. Importantly, the female-specific sequences and female heterozygous SNP loci indicate that a female heterogametic and male homogametic ZW/ZZ sex-determination system should exist in M. nudus. The results provide a solid basis for revealing the sex-determination mechanism of this species, and open up new possibilities for developing sex-control breeding in sea urchin.

scholarly journals Cytogenetics of the Brazilian whiptail lizard Cnemidophorus littoralis (Teiidae) from a restinga area (Barra de Maricá) in Southeastern Brazil

2004 ◽  
Vol 64 (3b) ◽  
pp. 661-667 ◽  
Author(s):  
D. Peccinini-Seale ◽  
C. F. D. Rocha ◽  
T. M. B. Almeida ◽  
A. F. B. Araújo ◽  
M. A. De Sena
Keyword(s):  
New Species ◽  
Sex Determination ◽  
Diploid Number ◽  
Nucleolar Organizer ◽  
Southeastern Brazil ◽  
Nucleolar Organizer Regions ◽  
Interphase Nuclei ◽  
Determination Mechanism ◽  
A New Species ◽  
Chromosomal Sex Determination

Chromosomes of Cnemidophorus littoralis, a new species of teiid lizard recently described, were studied. The animals are from a restinga area in Barra de Maricá, RJ. The karyotype presents a diploid number of 2n = 46 chromosomes and a chromosomal sex determination mechanism of the type XX:XY. Nucleolar organizer regions, Ag-NORs, are at the sixth pair of chromosomes; there is variability of size and number of the Ag-stained nucleoli on the 50 interphase nuclei for each specimen analyzed. These nucleoli are related to NOR patterns that also demonstrated variability in size and number. This paper presents the first description of the karyotype of Cnemidophorus littoralis and of a chromosomal sex determination mechanism of the XX:XY type in the genus Cnemidophorus from Southeastern Brazil.

Life history, trophic behavior, and description of Gamasellodes vermivorax n. sp. (Mesostigmata: Ascidae), a predator of nematodes and arthropods in semiarid grassland soils

1987 ◽  
Vol 65 (7) ◽  
pp. 1689-1695 ◽  
Author(s):  
David Evans Walter
Keyword(s):  
Life History ◽  
Sex Determination ◽  
Adult Female ◽  
Generation Time ◽  
Life Stages ◽  
Adult Males ◽  
Microcosm Experiment ◽  
Grassland Soils ◽  
Semiarid Grassland ◽  
Determination Mechanism

All life stages of Gamasellodes vermivorax n. sp. (Mesostigmata: Ascidae), a predator of mites, collembolans, and nematodes in semiarid grassland soils, are described. Female to female generation time is 10 days on a diet of rhabditid nematodes at 24 °C. Each adult female may produce one to three eggs daily for at least 2 weeks. Female deutonymphs are guarded by adult males. Isolated female deutonymphs molt to adults which begin laying eggs within 48 h of emergence. All eggs laid by unfertilized females develop into males, indicating a haplodiploid sex determination mechanism. In a microcosm experiment, nematode densities were negatively correlated with G. vermivorax densities.

Evidence for a Genomic Imprinting Sex Determination Mechanism in Nasonia vitripennis (Hymenoptera; Chalcidoidea)

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 233-242 ◽  
Author(s):  
Stephen L Dobson ◽  
Mark A Tanouye
Keyword(s):  
Sex Determination ◽  
Genomic Imprinting ◽  
Parasitic Wasp ◽  
Nasonia Vitripennis ◽  
Crossing Experiments ◽  
Proposed Model ◽  
Early Embryos ◽  
Study Support ◽  
Determination Mechanism ◽  
Paternal Sex Ratio

AbstractFive different models have been proposed for the sex determination mechanism of Chalcidoidea (Hymenoptera). Except for the most recently proposed model (genomic imprinting sex determination; GISD), each of these models has required complicating additions to explain observed phenomena. This report provides the first experimental test of the GISD model while simultaneously examining the four previously proposed models of sex determination. This test utilizes the parasitic wasp Nasonia vitripennis, crossing polyploid females with males harboring the paternal sex ratio chromosome (PSR). The results of this study support the GISD model as the mechanism of sex determination in Chalcidoidea. Specifically, crosses demonstrate that sex determination is independent of embryonic heterozygosity, ploidy, and gametic syngamy but is directly correlated with the embryonic presence of correctly imprinted chromosomes of paternal origin. These crossing experiments also provide information about the poorly characterized mechanisms of PSR, a supernumerary chromosome that induces paternal autosome loss in early embryos. The results demonstrate that the poor transmission of PSR through females is not a result of the ploidy of the host but of an alternative sex-dependent process. Crossing data reveal that PSR consistently induces the loss of the entire paternal complement that it accompanies, regardless of whether this complement is haploid or diploid.

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