Risks involved in fecal DNA-based genotyping of microsatellite loci in the Amur tiger Panthera tigris altaica:a pilot study

In modern wildlife ecological research,feces is the most common non-invasive source of DNA obtained in the field and polymerase chain reaction(PCR) technology based on microsatellite markers is used to mine genetic information contained within.This is especially the case for endangered species.However,there are risks associated with this genotyping method because of the poor quality of fecal DNA.In this study,we assessed genotyping risk across 12 microsatellite loci commonly used in previous tiger studies using blood and fecal DNA from captive Amur tigers(Panthera tigris altaica).To begin,we developed an index termed the accumulated matching rate of genotypes(R)between positive DNA(blood samples) and fecal DNA to explore the correct genotyping probability of a certain microsatellite locus.We found that different microsatelliteloci had different genotyping risks and required different PCR amplification protocols.The genotyping errors we detected altered population genetic parameters and potentially impact subsequent analyses.Based on these findings,we recommend that:(1) four loci(E7,Fca094,Pti007 and Pti010) of 12 loci are not suitable for Amur tiger genetic research because of a low Rand difficulty reaching a stable status;(2) the Rof the 12 microsatellite loci plateaued differently,and considering limited budgets,amplification times of some loci could be increased when using fecal samples; and(3) future genetic analysis of wild Amur tigers should be corrected by genotyping error rates(1-R).

Risk assessment of Giardia from a full scale MBR sewage treatment plant caused by membrane integrity failure

Membrane bioreactors（MBR） are highly efficient at intercepting particles and microbes and have become an important technology for wastewater reclamation. However, many pathogens can accumulate in activated sludge due to the long residence time usually adopted in MBR, and thus may pose health risks when membrane integrity problems occur.This study presents data from a survey on the occurrence of water-borne Giardia pathogens in reclaimed water from a full-scale wastewater treatment plant with MBR experiencing membrane integrity failure, and assessed the associated risk for green space irrigation. Due to membrane integrity failure, the MBR effluent turbidity varied between 0.23 and 1.90 NTU over a period of eight months. Though this turbidity level still met reclaimed water quality standards（≤ 5 NTU）, Giardia were detected at concentrations of 0.3 to 95 cysts/10 L, with a close correlation between effluent turbidity and Giardia concentration. All β-giardin gene sequences of Giardia in the WWTP influents were genotyped as Assemblages A and B, both of which are known to infect humans. An exponential dose–response model was applied to assess the risk of infection by Giardia. The risk in the MBR effluent with chlorination was9.83 × 10-3, higher than the acceptable annual risk of 1.0 × 10^-4. This study suggested that membrane integrity is very important for keeping a low pathogen level, and multiple barriers are needed to ensure the biological safety of MBR effluent.

Investigation of the association between all-trans-retinol dehydrogenase (RDH8) polymorphisms and high myopia in Chinese

Retinoic acid level in the retina/choroid is altered in induced myopia models.All-trans-retinol dehydrogenase(RDH8) is an important enzyme of retinoic acid metabolism.This study aimed to investigate the association of the RDH8 gene with high myopia.Three single nucleotide polymorphisms(SNPs) [RDH851(rs2233789) ,RDH8E5a(rs1644731) ,and RDH855b(rs3760753) ]were selected,based on the linkage disequilibrium pattern of RDH8 from a previous study,and genotyped for 160 Han Chinese nuclear families with highly myopic(-10 diopters or worse) offspring as well as in an independent group with 166 highly myopic cases(-10 diopters or worse) and 211 controls. Family-based association analysis was performed using the family-based association test(FBAT) package,and genotype relative risk(GRR) was calculated using the GenAssoc program.Population-based association analysis was performed using Chi-square test.These SNPs were in linkage equilibrium with each other.SNPs RDH851(rs2233789) and RDH8E5a(rs1644731) both did not show association with high myopia.SNP RDH855b(rs3760753) demonstrated significant association(P=0.0269) with a GRR of 0.543(95%confidence interval=0.304-0.968,P=0.038) .The association became statistically insignificant,however,after multiple comparison correction.Haplotype analysis did not show a significant association either.Population-based association analysis also showed no significant association(P>0.05) .Our family-and population-based data both suggest that the RDH8 gene is unlikely to be associated with high myopia in Chinese.