A detection model of testis-derived circular RNAs in serum for predicting testicular sperm retrieval rate in non-obstructive azoospermia patients

BACKGROUND

Microdissection testicular sperm extraction is an effective method to retrieve sperm from non-obstructive azoospermia patients. However, its successful rate is less than 50%.

OBJECTIVES

To identify the predictive value of circular RNAs in serum for sperm retrieval rate in non-obstructive azoospermia patients.

MATERIALS AND METHODS

180 non-obstructive azoospermia patients were recruited in this study, including 84 individuals with successful sperm retrieval and 96 individuals with failed sperm retrieval. Our study contained two phases. First, 20 patients, selected from the 180 patients, were included in screening cohort. In this cohort, the top 20 circular RNAs from our previous testicular circRNA profiles were verified between successful and failed sperm retrieval groups using real-time polymerase chain reaction. Six circular RNAs with the most significantly different expressions were selected for further verification. Second, the 180 patients were included as discovery cohort to verify the six circular RNAs. Circular RNAs were extracted from serum in each participant. Logistic regression analysis was further performed to identify the predictive value and the area under the curve analysis was used to evaluate diagnostic efficiency, sensitivity, and specificity.

RESULTS

Six circular RNAs including hsa_circ_0058058, hsa_circ_0008045, hsa_circ_0084789, hsa_circ_0000550, hsa_circ_0007422, and hsa_circ_0004099 showed aberrant expressions between the successful and failed sperm retrieval group. In addition, both single-circular RNA panels and multi-circular RNA panels were finally verified to be significant in predicting sperm retrieval rate. Notably, multi-circular RNAs panels demonstrated better predictive abilities compared with single-circRNA panels, and the combined panel of six-circular RNAs (risk score = 1.094×hsa_circ_0058058+0.697×hsa_circ_0008045+0.718×hsa_circ_0084789-0.591×hsa_circ_0000550-0.435×hsa_circ_0007422-1.017×hsa_circ_0004099-1.561) exhibited the best predictive ability in the present study with an AUC of 0.977, a sensitivity of 91.7% and a specificity of 86.5%. A higher risk score indicated a higher risk of failure in sperm retrieval.

DISCUSSION AND CONCLUSION

Our study was the first to report that testis-derived circular RNAs in serum have the ability to predict sperm retrieval rate in non-obstructive azoospermia patients, whether it is a single-circular RNA or a combination of multi-circular RNAs.

In situ Western hybridization: a new, highly sensitive technique to detect foreign and endogenous protein distribution in rice seeds

We have developed a highly sensitive in situ Western hybridization technique to study tissue-specific expression of foreign and endogenous genes in transgenic and non-transformed rice seed. The expression pattern of the soybean ferritin gene directed by a rice glutelin gene promoter, GluB-1, in transgenic rice seed revealed by this method was exactly the same as that revealed by immunological tissue printing but much clearer than the latter, and corresponded well to the results of GluB-1 promoter characterization studies. This method provides an alternative choice for studying the tissue-specific expression of a promoter, omitting the complicated transgenic procedure. The method can also be used to study the expression and accumulation pattern of endogenous genes, such as glutelin and prolamine genes, in non-transformed plants.

Biochemical and molecular characterization of a rice glutelin allele for the GluA-1 gene

The rice ( Oryza sativa L.) mutant of glu4a, lacking the glutelin alpha-2 subunit while the alpha-1 subunit increased (alpha-1H/alpha-2L), was used in this study. Two-dimensional electrophoresis analysis revealed that the mutant lacked the polypeptide pI6.71/alpha-2 encoded by glu4 while forming a new polypeptide of pI6.50/alpha-1. Experiments were conducted to identify the relationships between the mutated polypeptides of the mutant and to illustrate the mutation mechanism of the allele. Peptide mapping and amino-acid sequence analyses revealed that the newly formed glu4a encoded polypeptide pI6.50/alpha-1 of high homology with the deleted pI6.71/alpha-2 polypeptide which was encoded by glu4 (GluA-1). The nucleotide sequence revealed that the iso-electric point variation of the pI6.50/alpha-1 polypeptide was caused by a point mutation with nucleotide replacement at the variable region of the gene. These results suggested the possibility of altering glutelin quality by using single gene mutation.

Improved electrophoretical analyses for rice seed storage glutelin

Rice seed storage glutelin could be separated into three acidic (alpha-) and three basic (beta-) subunit components by SDS-PAGE using 15%-25% gradient acrylamide gel. More than 13 acidic and 14 basic bands may be distinguished with an improved iso-electric focus electrophoresis system by adjusting Ampholine ratios. Combine these two sensitive electrophoresis systems resulting in two-dimensional electrophoresis giving high resolution of glutelin leading the yield of single polypeptide. The improved electrophoresis system is helpful in identifying rice glutelin variation and for further studies of glutelin biochemistry.

New rice mutants lacking glutelin alpha-1 subunit

Four rice (Oryza sativa L.) mutant lines lacking glutelin alpha-1 subunit were obtained by screening the progenies of fertilized egg treatment with MNU. SDS-PAGE and IEF analyses showed that the mutants without pI6.82 polypeptide in common while forming/increasing other polypeptide indicating that the mutants were controlled by structural genes. IEF analysis also suggested that the polypeptides of pI6.82 and pI8.58 derived from the same glutelin precursor. The mutants are considered to be useful material for glutelin quality improvement and for genetic regulatory mechanism study of glutelin biosynthesis.