Comment on “Absence of sperm RNA elements correlates with idiopathic male infertility”

Cappallo-Obermann, Heike; Spiess, Andrej‐Nikolai

doi:10.1126/scitranslmed.aaf2396

Cited by 7 publications

(2 citation statements)

References 12 publications

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“…It was only a year ago that sperm RNA cargo was placed center stage as a potential modifier of embryo development, a situation now being revisited in view of possible contamination in the semen preparations used for that study [6]. Whatever cargo human sperm is eventually shown to contain, increasing concerns that perturbations at the epigenetic level underscore the disturbing trend towards oligospermia all too evident in industrialized countries of the world are to be taken to heart as ARTs move forward [7].…”

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confidence: 99%

From preformation to reformulation—the then and now of sperm selection

Albertini

2017

J Assist Reprod Genet

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confidence: 99%

From preformation to reformulation—the then and now of sperm selection

Albertini

2017

J Assist Reprod Genet

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“…Nevertheless, the technical comment (3) suggested that a high proportion of somatic transcripts reside in spermatozoal RNA sequencing (RNA-seq) data sets and now microarray data when sperm were purified using a 50% density gradient, which yields a sperm and/or spermenriched fraction (1,7). In sperm, several RNA singularities should be considered before analyzing total RNA-seq data.…”

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Response to Comment on “Absence of sperm RNA elements correlates with idiopathic male infertility”

et al. 2016

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RNAs from other cell types have minimal impact on male fecundity-associated sperm RNA elements.The objective of the study by Jodar et al.(1) was to examine the general sperm transcript profile from different patients with idiopathic infertility presenting with normal semen parameters. Reference values of sperm parameters established by the World Health Organization in 2010 are at least 39 million sperm per ejaculate with 32% motility and 4% normal morphology (2). Accordingly, normal semen samples could present with 96% morphologically abnormal and 68% immotile sperm, indicating the heterogeneity of sperm population in each individual.The technical comment from Cappallo-Obermann and Spiess (3) suggests that the samples used in Jodar et al. (1) also contained different somatic cell types. This assertion may reflect their past experience within their patient population, where 30% of the samples have a round cell concentration of >5 × 10 6 /ml. In contrast, the clinic from which most samples were obtained reported that only 4% of patients (49 individuals from 1230 unselected nonazoospermic patients) presented a round cell concentration of >1 × 10 6 /ml (4). It is important to emphasize that all samples included in the study of Jodar et al.(1) had a round cell count of <1 × 10 6 /ml before PureSperm gradient purification, with the exception of a single sample. This is substantially lower than the reference values recommended by the World Health Organization (2). In addition, none of the samples included in the study had a notable number of epithelial cells or other identifiable cells, as evaluated by optical microscopy after PureSperm (table S1).Approaches to purify spermatozoa from semen such as swim-up (5) and density gradient centrifugation above 50% markedly decrease the recovery of spermatozoa. This is consistent with the physiological selection of the sperm. Moreover, as suggested by the decreased recovery of mitochondrial RNAs, somatic cell lysis buffer treatment likely compromises the midpiece of spermatozoa (6). Because the samples used in the study contained very low numbers of somatic cells, we chose the 50% PureSperm methodology for sperm purification. This minimized sperm selection while maintaining the integrity of spermatozoa. In those cases where round cells were detected by optical microscopy after the initial gradient, the 50% PureSperm gradient was repeated. Their efficient removal was verified by CD45/PTPRC reverse transcription polymerase chain reaction (RT-PCR) (table S1 and fig. S1).Nevertheless, the technical comment (3) suggested that a high proportion of somatic transcripts reside in spermatozoal RNA sequencing (RNA-seq) data sets and now microarray data when sperm were purified using a 50% density gradient, which yields a sperm and/or spermenriched fraction (1, 7). In sperm, several RNA singularities should be considered before analyzing total RNA-seq data. One must consider the background level present in any total sperm RNA-seq data. The absolute abundance of sperm transcripts, including ...

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