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.

scholarly journals Evolution of Sex Determination in Caenorhabditis: Unusually High Divergence of tra-1 and Its Functional Consequences

Genetics ◽  
1996 ◽  
Vol 144 (2) ◽  
pp. 587-595 ◽  
Author(s):  
Mario de Bono ◽  
Jonathan Hodgkin
Keyword(s):  
Sex Determination ◽  
Germ Line ◽  
Amino Acid Identity ◽  
Evolution Of Sex ◽  
Phenotypic Differences ◽  
C Elegans ◽  
Functional Studies ◽  
Somatic Gonad ◽  
Functional Consequences ◽  
Significant Divergence

Abstract The tra-1 gene is a terminal regulator of somatic sex in Caenorhabditis elegans: high tra-1 activity elicits female development, low tra-1 activity elicits male development. To investigate the function and evolution of tra-1, we examined the tra-1 gene from the closely related nematode C. briggsae. Ce-tra-1 and Cb-tra-1 are unusually divergent. Each gene generates two transcripts, but only one of these is present in both species. This common transcript encodes TRA-1A, which shows only 44% amino acid identity between the species, a figure much lower than that for previously compared genes. A Cb-tra-1 transgene rescues many tissues of tra-1(nul1) mutants of C. elegans but not the somatic gonad or germ line. This transgene also causes nongonadal feminization of XO animals, indicating incorrect sexual regulation. Alignment of Ce-TRA-1A and Cb-TRA-1A defines several conserved regions likely to be important for tra-1 function. The phenotypic differences between Ce-tra-1(null) mutants rescued by Cb-tra-1 transgenes and wild-type C. elegans indicate significant divergence of regulatory regions. These molecular and functional studies suggest that evolution of sex determination in nematodes is rapid and genetically complex.

scholarly journals ampG Gene of Pseudomonas aeruginosa and Its Role in β-Lactamase Expression

2010 ◽  
Vol 54 (11) ◽  
pp. 4772-4779 ◽  
Author(s):  
Ying Zhang ◽  
Qiyu Bao ◽  
Luc A. Gagnon ◽  
Ann Huletsky ◽  
Antonio Oliver ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Amino Acid ◽  
Transmembrane Protein ◽  
Amino Acid Identity ◽  
Clinical Isolates ◽  
Signal Molecules ◽  
Carbonyl Cyanide ◽  
Increased Sensitivity ◽  
Potential Strategy ◽  
High Level

ABSTRACT In enterobacteria, the ampG gene encodes a transmembrane protein (permease) that transports 1,6-GlcNAc-anhydro-MurNAc and the 1,6-GlcNAc-anhydro-MurNAc peptide from the periplasm to the cytoplasm, which serve as signal molecules for the induction of ampC β-lactamase. The role of AmpG as a transporter is also essential for cell wall recycling. Pseudomonas aeruginosa carries two AmpG homologues, AmpG (PA4393) and AmpGh1 (PA4218), with 45 and 41% amino acid sequence identity, respectively, to Escherichia coli AmpG, while the two homologues share only 19% amino acid identity. In P. aeruginosa strains PAO1 and PAK, inactivation of ampG drastically repressed the intrinsic β-lactam resistance while ampGh1 deletion had little effect on the resistance. Further, deletion of ampG in an ampD-null mutant abolished the high-level β-lactam resistance that is associated with the loss of AmpD activity. The cloned ampG gene is able to complement both the P. aeruginosa and the E. coli ampG mutants, while that of ampGh1 failed to do so, suggesting that PA4393 encodes the only functional AmpG protein in P. aeruginosa. We also demonstrate that the function of AmpG in laboratory strains of P. aeruginosa can effectively be inhibited by carbonyl cyanide m-chlorophenylhydrazone (CCCP), causing an increased sensitivity to β-lactams among laboratory as well as clinical isolates of P. aeruginosa. Our results suggest that inhibition of the AmpG activity is a potential strategy for enhancing the efficacy of β-lactams against P. aeruginosa, which carries inducible chromosomal ampC, especially in AmpC-hyperproducing clinical isolates.

scholarly journals Multiple horizontal acquisitions of plant genes in the whitefly Bemisia tabaci

2022 ◽  
Author(s):  
Clément Gilbert ◽  
Florian Maumus
Keyword(s):  
Bemisia Tabaci ◽  
Control Strategies ◽  
Purifying Selection ◽  
Amino Acid Identity ◽  
Current Control ◽  
Eukaryote Evolution ◽  
Plant Genes ◽  
Insect Interactions ◽  
High Level ◽  
Open Question

The extent to which horizontal gene transfer (HGT) has shaped eukaryote evolution remains an open question. Two recent studies reported four plant-like genes acquired through two HGT events by the whitefly Bemisia tabaci, a major agricultural pest (Lapadula et al. 2020; Xia et al. 2021). Here, we performed a systematic search for plant-to-insect HGT in B. tabaci and uncovered a total of 50 plant-like genes deriving from at least 24 independent HGT events. Most of these genes are present in three cryptic B. tabaci species, show high level of amino-acid identity to plant genes (mean = 64%), are phylogenetically nested within plant sequences, and are expressed and evolve under purifying selection. The predicted functions of these genes suggest that most of them are involved in plant-insect interactions. Thus, substantial plant-to-insect HGT may have facilitated the evolution of B. tabaci towards adaptation to a large host spectrum. Our study shows that eukaryote-to-eukaryote HGT may be relatively common in some lineages and it provides new candidate genes that may be targeted to improve current control strategies against whiteflies.

scholarly journals THE CONCEPT OF BUILDING OF ECONOMIC ENSURING POLICY THE COMPETITIVENESS OF INNOVATIVE BUSINESSES IS FORMED AT THE MACRO AND MICRO LEVELS

2021 ◽  
Author(s):  
Iryna Zrybnieva
Keyword(s):  
Innovation Activity ◽  
Competitive Advantages ◽  
Resource Potential ◽  
Economic Entity ◽  
Marketing Orientation ◽  
Factors Influencing ◽  
Long Run ◽  
High Level ◽  
Key Aspects ◽  
Market Relations

With the development of market relations, growing uncertainty and risk, the high level of competitiveness of the enterprise largely depends on the level of its innovation activity. In this article the author described the factors influencing the formation of the competitive potential of the subjects of innovative entrepreneurship, carried out their classification. In his opinion, the competitiveness of innovative entrepreneurs depends primarily on the economic situation achieved through economic strategy (policy). The economic policy of ensuring the competitiveness of the subjects of innovative entrepreneurship is formed both at the macroeconomic and microeconomic level. At each level of management requires a special organizational and economic approach that ensures the transformation of available resources into competitive advantages through the use of certain competencies. The author concludes that the achievement of competitive advantages in the market in the future and high competitiveness of the enterprise in the long run are possible due to efficient use of resource potential, high strategic opportunities to reproduce resource potential, strategic marketing orientation of the product offer. With the growth of the dynamics of competitiveness of the studied subject of innovative entrepreneurship, it is necessary to determine its position in the internal environment, ie to identify how the current ability to compete corresponds to the opportunities present in the external environment. With declining dynamics (as an option – the lack of dynamics), including those obtained in the current assessment of competitiveness, it is necessary to first identify the reasons for the decline in the competitiveness of the subject of innovative entrepreneurship. Given that the assessment of competitiveness integrates three key aspects, the reasons, respectively, can be social, economic or technological in nature (or be characterized by a combination of them). Competitiveness as an internal mechanism of effective activity of an economic entity transforms the market into a system of factors influencing the process of competition, thereby forming competitiveness in the field of a separate competitive field.

scholarly journals A compendium of novel genomics technologies provides a chromosome-scale assembly and insights into the sex determining system of the Greenland Halibut

2021 ◽  
Author(s):  
Anne-Laure Ferchaud ◽  
Claire Merot ◽  
Eric Normandeau ◽  
Ioannis Ragoussis ◽  
Charles Babin ◽  
...  
Keyword(s):  
Sex Determination ◽  
Single Molecule ◽  
Sex Chromosome ◽  
Major Effect ◽  
Whole Genome Sequence ◽  
Greenland Halibut ◽  
Long Reads ◽  
Full Picture ◽  
High Conservation ◽  
High Level

Despite the commercial importance of Greenland Halibut (Reinhardtius hippoglossoides), important gaps still persist in our knowledge of this species, including its reproductive biology and sex determination mechanism. In this study, we combined single molecule sequencing of long reads (Pacific Sciences) with Chromatin Conformation Capture sequencing (Hi-C) data to provide the first chromosome-level genome reference for this species. The high-quality assembly encompassed more than 598 Megabases (Mb) assigned to 1 594 scaffolds (scaffold N50 = 25 Mb) with 96 % of its total length distributed among 24 chromosomes. The investigation of its syntenic relationships with other economically important flatfish species revealed a high conservation of synteny blocks among members of this phylogenetic clade. Sex determination analysis revealed that flatfishes do not escape the rule applied to other teleost fish and exhibit a high level of plasticity and turnover in sex-determination mechanisms. A whole-genome sequence analysis of 198 individuals allowed us to draw a full picture of the molecular sex determination (SD) system for Greenland Halibut, revealing that this species possesses a very nascent male heterogametic XY system, with a putative major effect of the sox2 gene, also described as the main SD driver in two other flatfishes. Interestingly, our study also suggested for the first time in flatfishes that a putative Y-autosomal fusion could be associated with a reduction of recombination typical of early steps of sex chromosome evolution.

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 Evidence That Runt Acts as a Counter-Repressor of Groucho During Drosophila melanogaster Primary Sex Determination

2020 ◽  
Vol 10 (7) ◽  
pp. 2487-2496
Author(s):  
Sharvani Mahadeveraju ◽  
Young-Ho Jung ◽  
James W. Erickson
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Determination ◽  
Transcriptional Repression ◽  
Biological Effects ◽  
Regulatory Gene ◽  
Animal Cells ◽  
Interaction Domain ◽  
Link Type ◽  
High Level ◽  
Runx Proteins

Runx proteins are bifunctional transcription factors that both repress and activate transcription in animal cells. Typically, Runx proteins work in concert with other transcriptional regulators, including co-activators and co-repressors to mediate their biological effects. In Drosophila melanogaster the archetypal Runx protein, Runt, functions in numerous processes including segmentation, neurogenesis and sex determination. During primary sex determination Runt acts as one of four X-linked signal element (XSE) proteins that direct female-specific activation of the establishment promoter (Pe) of the master regulatory gene Sex-lethal (Sxl). Successful activation of SxlPe requires that the XSE proteins overcome the repressive effects of maternally deposited Groucho (Gro), a potent co-repressor of the Gro/TLE family. Runx proteins, including Runt, contain a C-terminal peptide, VWRPY, known to bind to Gro/TLE proteins to mediate transcriptional repression. We show that Runt’s VWRPY co-repressor-interaction domain is needed for Runt to activate SxlPe. Deletion of the Gro-interaction domain eliminates Runt-ability to activate SxlPe, whereas replacement with a higher affinity, VWRPW, sequence promotes Runt-mediated transcription. This suggests that Runt may activate SxlPe by antagonizing Gro function, a conclusion consistent with earlier findings that Runt is needed for Sxl expression only in embryonic regions with high Gro activity. Surprisingly we found that Runt is not required for the initial activation of SxlPe. Instead, Runt is needed to keep SxlPe active during the subsequent period of high-level Sxl transcription suggesting that Runt helps amplify the difference between female and male XSE signals by counter-repressing Gro in female, but not in male, embryos.

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

Change through continuity:a quiet revolution in primary health care in New Zealand

2005 ◽  
Vol 29 (4) ◽  
pp. 380 ◽  
Author(s):  
Toni Ashton
Keyword(s):  
New Zealand ◽  
Health System ◽  
Structural Changes ◽  
Health Sector ◽  
Major Change ◽  
System Reform ◽  
Whole Process ◽  
And Performance ◽  
High Level ◽  
Key Aspects

IN A RECENTLY PUBLISHED paper entitled Continuity through change: the rhetoric and reality of health reform in New Zealand, I and my co-authors Nick Mays and Nancy Devlin pointed out that, in spite of a series of major health sector reforms during the 1990s and early 2000s, some key aspects of the system have endured.1 Moreover, many incremental changes to existing processes and systems that occurred during the reform period have, arguably, been more important to improving the functioning and performance of the system than the more high level (and more visible) structural changes. Since that paper was written, many further changes have occurred in the organisation, funding and management of the New Zealand health system. However, in contrast to the 1990s, the focus now is on continuity and stability rather than on any need for further major change. Indeed, terms such as ?reform? or ?restructuring? have now all but vanished from any debate about health policy in New Zealand. Perhaps the reformers have learned that health system reform is akin to training for the Olympics. The whole process takes a fair bit of time and effort, and results are unlikely to be achieved in the short term. Further major reform is also not regarded as politically viable. As noted in an article in the New Zealand Herald just before the general election in September, there is ?. . . considerable public sensitivity over any whiff of restructuring in health?.2

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