scholarly journals Synthetic Sex Ratio Distorters Based on Crispr for the Control of Harmful Insect Populations

2021 ◽  
pp. 843-855
Author(s):  
B. Fasulo ◽  
A. Meccariello ◽  
P. A. Papathanos ◽  
A. Windbichler
Keyword(s):  
Sex Ratio ◽  
Insect Populations ◽  
Harmful Insect

scholarly journals redkmer: an assembly-free pipeline for the identification of abundant and specific X-chromosome target sequences for X-shredding by CRISPR endonucleases

2017 ◽  
Author(s):  
Philippos Aris Papathanos ◽  
Nikolai Windbichler
Keyword(s):  
Sex Ratio ◽  
X Chromosome ◽  
Single Molecule ◽  
Sex Chromosome ◽  
Insect Pest ◽  
Gene Array ◽  
Ribosomal Gene ◽  
Long Reads ◽  
Target Sequences ◽  
Harmful Insect

AbstractCRISPR-based synthetic sex ratio distorters, that operate by shredding the X-chromosome during male meiosis, are promising tools for the area-wide control of harmful insect pest or disease vector species. However, the selection of gRNA targets, in the form of high-copy sequence repeats on the X chromosome of a given species, is difficult since such repeats are not accurately resolved in genome assemblies and can’t be assigned to chromosomes with confidence. We have therefore developed the redkmer computational pipeline, designed to identify short and highly-abundant sequence elements occurring uniquely on the X-chromosome. Redkmer was designed to use as input exclusively raw WGS data from males and females. We tested redkmer with suitable short and long read WGS data ofAn. gambiae, the major vector of human malaria, in which the X-shredding paradigm was originally developed. Redkmer establishes long reads as chromosomal proxies with excellent correlation to the genome assembly and uses them to rank X-candidate kmers for their level of X-specificity and abundance. Redkmer identified a high-confidence set of 25-mers, many of which belong to previously known X-chromosome specific repeats ofAn. gambiae, including the ribosomal gene array and the selfish genetics elements harbored within it. WGS data from a control strain in which these repeats are also present on the Y chromosome confirmed the elimination of these kmers in the filtering steps. Finally, we show that redkmer output can be linked directly to gRNA selection and can also inform gRNA off-target prediction. The redkmer pipeline is designed to enable the generation of synthetic sex ratio distorters for the control of harmful insect species of medical or agricultural importance. It proceeds from WGS input data to deliver candidate X-specific CRISPR gRNA candidate target sequences. In addition the output of redkmer, including the prediction of chromosomal origin of single-molecule long reads and chromosome specific kmers, could also be used for the characterization of other biologically relevant sex chromosome sequences, a task that is frequently hampered by the repetitiveness of sex chromosome sequence content.

scholarly journals Resistance of Aedes aegypti to temephos and adaptive disadvantages

2014 ◽  
Vol 48 (5) ◽  
pp. 775-782 ◽  
Author(s):  
Morgana Michele Cavalcanti de Souza Leal Diniz ◽  
Alleksandra Dias da Silva Henriques ◽  
Renata da Silva Leandro ◽  
Dalvanice Leal Aguiar ◽  
Eduardo Barbosa Beserra
Keyword(s):  
Sex Ratio ◽  
Aedes Aegypti ◽  
Selection Pressure ◽  
Life Cycles ◽  
Adult Longevity ◽  
Larval Phase ◽  
Susceptible Population ◽  
Diagnostic Dose ◽  
Insect Populations ◽  
The City

OBJECTIVE To evaluate the resistance of Aedes aegypti to temephos Fersol 1G (temephos 1% w/w) associated with the adaptive disadvantage of insect populations in the absence of selection pressure. METHODS A diagnostic dose of 0.28 mg a.i./L and doses between 0.28 mg a.i./L and 1.40 mg a.i./L were used. Vector populations collected between 2007 and 2008 in the city of Campina Grande, state of Paraíba, were evaluated. To evaluate competition in the absence of selection pressure, insect populations with initial frequencies of 20.0%, 40.0%, 60.0%, and 80.0% resistant individuals were produced and subjected to the diagnostic dose for two months. Evaluation of the development of aquatic and adult stages allowed comparison of the life cycles in susceptible and resistant populations and construction of fertility life tables. RESULTS No mortality was observed in Ae. aegypti populations subjected to the diagnostic dose of 0.28 mg a.i./L. The decreased mortality observed in populations containing 20.0%, 40.0%, 60.0%, and 80.0% resistant insects indicates that temephos resistance is unstable in the absence of selection pressure. A comparison of the life cycles indicated differences in the duration and viability of the larval phase, but no differences were observed in embryo development, sex ratio, adult longevity, and number of eggs per female. CONCLUSIONS The fertility life table results indicated that some populations had reproductive disadvantages compared with the susceptible population in the absence of selection pressure, indicating the presence of a fitness cost in populations resistant to temephos.

scholarly journals Female bias in an immigratory population of Cnaphalocrocis medinalis moths based on field surveys and laboratory tests

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jia-Wen Guo ◽  
Fan Yang ◽  
Ping Li ◽  
Xiang-Dong Liu ◽  
Qiu-Lin Wu ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Laboratory Population ◽  
Cnaphalocrocis Medinalis ◽  
Energy Reserves ◽  
Field Surveys ◽  
Ratio Bias ◽  
Sex Ratio Bias ◽  
Insect Populations ◽  
Female Bias ◽  
Underlying Mechanisms

AbstractSex ratio bias is common in migratory animals and can affect population structure and reproductive strategies, thereby altering population development. However, little is known about the underlying mechanisms that lead to sex ratio bias in migratory insect populations. In this study, we used Cnaphalocrocis medinalis, a typical migratory pest of rice, to explore this phenomenon. A total of 1,170 moths were collected from searchlight traps during immigration periods in 2015–2018. Females were much more abundant than males each year (total females: total males = 722:448). Sex-based differences in emergence time, take-off behaviour, flight capability and energy reserves were evaluated in a laboratory population. Females emerged 0.78 days earlier than males. In addition, the emigratory propensity and flight capability of female moths were greater than those of male moths, and female moths had more energy reserves than did male moths. These results indicate that female moths migrate earlier and can fly farther than male moths, resulting more female moths in the studied immigratory population.

Die unbehandelten Kranken: Ältere Männer mit Depression

2008 ◽  
Vol 27 (07) ◽  
pp. 617-619 ◽  
Author(s):  
M. Wittmann ◽  
E. Haen ◽  
H. Spießl ◽  
H. Hausner
Keyword(s):  
Sex Ratio ◽  
Epidemiologische Studien

ZusammenfassungZahlreiche epidemiologische Studien zeigen, dass sich das Geschlechterverhältnis der Prävalenz depressiver Erkrankungen ab der 6. Lebensdekade – also nach der weiblichen Menopause – wieder annähert. Wir haben untersucht, ob sich dieser epidemiologische Effekt auch in der stationären Versorgung abbildet. Unter Verwendung der AGATE-Stichtagsdaten der Jahre 2000 bis 2004, wurde der Zusammenhang zwischen Geschlecht und Alter bei stationär behandelten depressiven Patienten analysiert. Der Zusammenhang zwischen Geschlechterverhältnis und dem Alter wurde mithilfe des Korrelationskoeffizienten nach Spearman sowie mit χ2-Test untersucht. In der 5. und 6. Lebensdekade lag die Sex-Ratio F/M bei 1,7:1, sie stieg in der 7. Dekade auf 2,2:1 und in der 8. Dekade auf 2,6:1 an. Anders als aufgrund epidemiologischer Studien zu erwarten wäre, nähert sich in der stationär psychiatrischen Versorgung das Verhältnis depressiver Patienten im Alter nicht an. Depressive ältere Männer sind also im stationären Versorgungssystem unterrepräsentiert.

The Sex Ratio in the Progeny of Oestrogen-Treated Parents in the Brown Leghorn

1958 ◽  
Vol 37 (2) ◽  
pp. 307-311 ◽  
Author(s):  
C. F. Pun
Keyword(s):  
Sex Ratio
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