scholarly journals Diagnosing Zygosity in Giant Panda Twins Using Short Tandem Repeats

2018 ◽  
Vol 21 (6) ◽  
pp. 527-532
Author(s):  
Maiju Qiao ◽  
Yingmin Zhou ◽  
Thomas Connor ◽  
Rengui Li ◽  
Dan Tang ◽  
...  
Keyword(s):  
Giant Panda ◽  
Tandem Repeats ◽  
Monozygotic Twins ◽  
Giant Pandas ◽  
West China ◽  
Conservation Effort ◽  
In Captivity ◽  
Mz Twins ◽  
Insight Into ◽  
Short Tandem

The giant panda, native to mountains of south-west China, is one of the world's rarest bear species and is subject to considerable conservation effort. In captivity, the proportion of twins accounts for 54% of the total number of births. To date, little is known about zygosity in panda populations — specifically, the proportion of monozygotic and dizygotic twins. In this study, we used 10 microsatellite markers for reliable zygosity testing, and the probability of monozygotic twins was 99.963% when all 10 markers were concordant. Out of 43 studied twin pairs, no MZ twins were found, indicating that there may be no identical panda twins (or the incidence is very low). We speculate that the fertilized eggs of giant pandas do not have the capability to split into two identical embryos, or that this ability is very poor, which is likely due to delayed implantation that is common in bear species. The results of this study deepen our understanding of giant panda breeding, yield insight into panda twins’ likely mechanism of formation, and reduce the uncertainty of individual identity in wild population surveys.

Giant panda (Ailuropoda melanoleuca) spermatozoon decondensation in vitro is not compromised by cryopreservation

2006 ◽  
Vol 18 (7) ◽  
pp. 767 ◽  
Author(s):  
Rebecca E. Spindler ◽  
Huang Yan ◽  
JoGayle Howard ◽  
Wang PengYan ◽  
Zhang Hemin ◽  
...  
Keyword(s):  
Giant Panda ◽  
Acrosome Reaction ◽  
Ailuropoda Melanoleuca ◽  
Genetic Management ◽  
Giant Pandas ◽  
Before And After ◽  
In Captivity ◽  
Oocyte Cytoplasm ◽  
Natural Breeding

Natural breeding of giant pandas in captivity is compromised, making artificial insemination and spermatozoa cryopreservation essential for genetic management. This study examined the influence of freeze–thawing on traditional parameters such as motility and spermatozoon functionality, specifically decondensation in vitro. Giant panda spermatozoa were assessed before and after rapid cryopreservation (4°C to –130°C over 2 min) in liquid nitrogen vapour. Spermatozoa pre-incubated in medium for 6 h were co-incubated with cat zonae (2 zonae μL–1) for 30 min to effect capacitation and an acrosome reaction. Spermatozoa were then mixed with mature cat oocyte cytoplasm (2 cytoplasm μL–1) for 4 h and evaluated for decondensation. Frozen spermatozoa were less motile (P < 0.05) than fresh counterparts immediately post-thawing, but not after 6 h incubation. There were more (P < 0.05) spermatozoa with completely diffused chromatin post-thaw (10.4 ± 1.3%; mean ± s.e.m.) compared to fresh counterparts (5.1 ± 1.0%). However, there was no overall difference (P > 0.05) in the incidence of decondensation between fresh (4 h, 69.8 ± 5.9%) and thawed (4 h, 71.5 ± 4.9%) spermatozoa after exposure to cat oocyte cytoplasm. It is concluded that the ‘rapid’ method now used to cryopreserve giant panda spermatozoa has little impact on spermatozoon decondensation.

Monozygotic twins: Identical or distinguishable for science and law?

2021 ◽  
Vol 61 (1_suppl) ◽  
pp. 62-66
Author(s):  
Stefania Turrina ◽  
Elena Bortoletto ◽  
Giacomo Giannini ◽  
Domenico De Leo
Keyword(s):  
Capillary Electrophoresis ◽  
Next Generation Sequencing ◽  
Tandem Repeats ◽  
Massively Parallel Sequencing ◽  
Forensic Genetics ◽  
Monozygotic Twins ◽  
Copy Number Variations ◽  
Next Generation ◽  
Generation Sequencing ◽  
Short Tandem

Monozygotic twins, also known as monovular twins, share an identical genetic heritage because they are two individuals who derive from the same zygote. For this reason, they have been considered indistinguishable. They represent a limit for the application of markers and analytical methods that are routinely used in forensic science because analyses of DNA fragments (short tandem repeats analysed by capillary electrophoresis) are unable to distinguish monozygotic twins. The recent introduction of ultra-deep next generation sequencing in forensic genetics, also known as massively parallel sequencing, has made it possible to identify a number of genetic variations through genome sequencing (such as copy number variations, single nucleotide polymorphisms and DNA methylation) that make it possible to distinguish monozygotic twins. Here, we present a case of ascertaining biological paternity, in which the alleged father had a monozygotic twin brother. This case led to the examination of international law in similar cases in which the only available biological evidence derives from classical forensic genetic analysis, performed with short tandem repeat (autosomal and/or gonosomal) capillary electrophoresis and the probative value, if recognised, of the next generation sequencing technology in the courtroom.

Population Genetics of Y-Chromosome Short Tandem Repeats in Humans

1997 ◽  
Vol 45 (3) ◽  
pp. 265-270 ◽  
Author(s):  
Anna Pérez-Lezaun ◽  
Francesc Calafell ◽  
Mark Seielstad ◽  
Eva Mateu ◽  
David Comas ◽  
...  
Keyword(s):  
Population Genetics ◽  
Y Chromosome ◽  
Short Tandem Repeats ◽  
Tandem Repeats ◽  
Short Tandem

Bayesian approach to discriminant problems for count data with application to multilocus short tandem repeat dataset

2020 ◽  
Vol 19 (2) ◽  
Author(s):  
Koji Tsukuda ◽  
Shuhei Mano ◽  
Toshimichi Yamamoto
Keyword(s):  
Sample Size ◽  
Classification Accuracy ◽  
Tandem Repeats ◽  
Bayes Factor ◽  
Characteristic Curve ◽  
Geometric Mean ◽  
Previous Method ◽  
Threshold Adjustment ◽  
Two Populations ◽  
Short Tandem

AbstractShort Tandem Repeats (STRs) are a type of DNA polymorphism. This study considers discriminant analysis to determine the population of test individuals using an STR database containing the lengths of STRs observed at more than one locus. The discriminant method based on the Bayes factor is discussed and an improved method is proposed. The main issues are to develop a method that is relatively robust to sample size imbalance, identify a procedure to select loci, and treat the parameter in the prior distribution. A previous study achieved a classification accuracy of 0.748 for the g-mean (geometric mean of classification accuracies for two populations) and 0.867 for the AUC (area under the receiver operating characteristic curve). We improve the maximum values for the g-mean to 0.830 and the AUC to 0.935. Computer simulations indicate that the previous method is susceptible to sample size imbalance, whereas the proposed method is more robust while achieving almost identical classification accuracy. Furthermore, the results confirm that threshold adjustment is an effective countermeasure to sample size imbalance.

Conditional Genotypic Probabilities for Microsatellite Loci

Genetics ◽  
2000 ◽  
Vol 155 (4) ◽  
pp. 1973-1980
Author(s):  
Jinko Graham ◽  
James Curran ◽  
B S Weir
Keyword(s):  
Short Tandem Repeats ◽  
Tandem Repeats ◽  
Dirichlet Distribution ◽  
Forensic Dna ◽  
Match Probability ◽  
Microsatellite Genotype ◽  
Allelic State ◽  
Forensic Assessments ◽  
Dna Profiles ◽  
Short Tandem

Abstract Modern forensic DNA profiles are constructed using microsatellites, short tandem repeats of 2–5 bases. In the absence of genetic data on a crime-specific subpopulation, one tool for evaluating profile evidence is the match probability. The match probability is the conditional probability that a random person would have the profile of interest given that the suspect has it and that these people are different members of the same subpopulation. One issue in evaluating the match probability is population differentiation, which can induce coancestry among subpopulation members. Forensic assessments that ignore coancestry typically overstate the strength of evidence against the suspect. Theory has been developed to account for coancestry; assumptions include a steady-state population and a mutation model in which the allelic state after a mutation event is independent of the prior state. Under these assumptions, the joint allelic probabilities within a subpopulation may be approximated by the moments of a Dirichlet distribution. We investigate the adequacy of this approximation for profiled loci that mutate according to a generalized stepwise model. Simulations suggest that the Dirichlet theory can still overstate the evidence against a suspect with a common microsatellite genotype. However, Dirichlet-based estimators were less biased than the product-rule estimator, which ignores coancestry.

scholarly journals Short Tandem Repeats Define a Gestational Origin for Metastatic Choriocarcinoma

2019 ◽  
Vol 108 (2) ◽  
pp. e115-e117
Author(s):  
Kelly Brown ◽  
Robert Homer ◽  
Marina Baine ◽  
Justin D. Blasberg
Keyword(s):  
Short Tandem Repeats ◽  
Tandem Repeats ◽  
Short Tandem
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