Male reproduction is affected by RNA interference of period and timeless in the desert locust Schistocerca gregaria

Identification and characterization of circadian clock genes in the head transcriptome of Conopomorpha sinensis Bradley

Conopomorpha sinensis Bradley is the most detrimental pest to litchi and longan in China. Adult eclosion, locomotion, mating and oviposition of C. sinensis usually occur at night, regulated by a circadian rhythm. Nevertheless, our understanding of the linkages between adult circadian rhythms and clock genes remains inadequate. To address this gap, transcriptomic analysis was conducted on female and male heads (including antennae) of C. sinensis using the Illumina HiSeq 6000 platform to identify major circadian clock-related genes. The annotated sequences were analyzed by BLASTx, and candidate clock genes were classified based on conservation, predicted domain architectures, and phylogenetic analysis. The analysis revealed a higher conservation of these genes among the compared moths. Further, the expression profile analysis showed a significant spatiotemporal and circadian rhythmic accumulation of some clock genes during development. The candidate clock genes were predominantly expressed in the head, highlighting their crucial function in circadian rhythm regulation. Moreover, CsinPer, CsinTim1, and CsinCry1 displayed similar dynamic expressions with a peak expression level in the 4th age adults, suggesting their involvement in regulation of courtship and mating behaviors. The CsinPer and CsinTim1 mRNA oscillated strongly with a similar phase, containing a peak expression just before the female mating peak. This work will greatly contribute to understanding the circadian clock system of C. sinensis and provide valuable information for further studies of the molecular mechanisms involved in rhythmicity in fruit-boring pests.

Circadian Activity and Clock Genes in Pachycrepoideus vindemmiae: Implications for Field Applications and Circadian Clock Mechanisms of Parasitoid Wasps

Despite the importance of circadian rhythms in insect behavior, our understanding of circadian activity and the molecular oscillatory mechanism in parasitoid wasp circadian clocks is limited. In this study, behavioral activities expected to be under the control of the endogenous circadian system were characterized in an ectoparasitoid wasp, Pachycrepoideus vindemmiae. Most adults exhibited emergence between late night and early morning, while mating only occurred during the daytime, with a peak at midday. Oviposition had three peaks in the early morning, late day, or early night and late night. Additionally, we identified eight putative clock genes from P. vindemmiae. The quantitative PCR (qPCR) results indicate that most clock genes showed significant rhythmic expressions. Our comparative analysis of clock genes in P. vindemmiae and 43 other parasitoid wasps revealed that none of the wasps possessed the timeless and cry1 genes commonly found in some other insect species, suggesting that the circadian clock system in parasitoid wasps is distinct from that in other non-Hymenoptera insects such as Drosophila. Thus, this study attempted to build the first hypothetical circadian clock model for a parasitoid wasp, thus generating hypotheses and providing a platform for the future functional characterization of P. vindemmiae clock genes as well as those of other parasitoid wasps. Finally, these findings on P. vindemmiae circadian activity will aid the development of effective field release programs for biological control, which can be tested under field conditions.

Identification and dynamic expression profiling of circadian clock genes in Spodoptera litura provide new insights into the regulation of sex pheromone communication

Spodoptera litura is an important pest that causes significant economic damage to numerous crops worldwide. Sex pheromones (SPs) mediate sexual communication in S. litura and show a characteristic degree of rhythmic activity, occurring mainly during the scotophase; however, the specific regulatory mechanisms remain unclear. Here, we employed a genome-wide analysis to identify eight candidate circadian clock genes in S. litura. Sequence characteristics and expression patterns were analyzed. Our results demonstrated that some circadian clock genes might regulate the biosynthesis and perception of SPs by regulating the rhythmic expression of SP biosynthesis-related genes and SP perception-related genes. Interestingly, all potential genes exhibited peak expression in the scotophase, consistent with the SP could mediate courtship and mating behavior in S. litura. Our findings are helpful in elucidating the molecular mechanism by which circadian clock genes regulate sexual communication in S. litura.

Men's Sleep Quality and Assisted Reproductive Technology Outcomes in Couples Referred to a Fertility Clinic: A Chinese Cohort Study

BACKGROUND

Poor sleep quality has been linked to lower semen quality, but it is unclear whether this result in decreased fertility. To address this question, we retrospectively evaluated the relationship between men's sleep quality and treatment outcomes in subfertile couples receiving assisted reproductive technology (ART).

PATIENT ENROLLMENT AND METHODS

From September 2017 to November 2019, 282 subfertile couples referred to a Chinese fertility clinic and eligible for ART procedures were enrolled in our study. Sociodemographic characteristics, life habits, and sleep habits in the year prior to ART were recorded. Sleep quality was measured using the Pittsburgh Sleep Quality Index (PSQI). We first divided the patients into two groups based on sleep quality (good sleep: PSQI < 5 and poor sleep: PSQI ≥ 5). Then, the ART outcomes (fertilization rate, good quality embryo rate, implantation rate, positive pregnancy rate, clinical pregnancy rate, live birth rate, miscarriage rate, and birth weight) of each group were analyzed. Finally, multivariate linear and logistic regression analysis were used to examine the relationship between sleep quality (discrete variable or dichotomous variable) and ART outcomes.

RESULTS

The participants in the poor sleep group showed a lower fertilization rate of 60.13% (543/903) when compared with 67.36% for the good sleep group (902/1339), P < 0.001. The global PSQI score had a significant influence on birth weight (β, -63.81; 95% CI, -119.91- -8.52; P = 0.047), and live birth rate (OR, 0.88; 95% CI, 0.78- 0.99; P = 0.047) after adjusting for the interfering factors. Men's sleep quality was unrelated to good quality embryos rate, implantation rate, positive pregnancy rate, clinical pregnancy rate, or miscarriage rate.

CONCLUSION

Men's sleep quality was positively associated with fertilization rate, birth weight, and live birth rate among couples undergoing ART.

Association Between Sleep Quality and Semen Parameters and Reproductive Hormones: A Cross-Sectional Study in Zhejiang, China

BACKGROUND

The effects of sleep duration on semen quality have been documented in many epidemiological studies. However, the association between sleep quality and semen parameters and reproductive hormones is still unclear.

PATIENTS ENROLLMENT AND METHODS

We conducted a cross-sectional study among 970 outpatients from the Reproductive Medicine Center in Zhejiang, China between October 2017 and July 2019. All participants delivered a semen sample, underwent a physical examination, and answered a questionnaire to provide the following information: demographics, life habits, and sleep habits. Sleep quality was measured using the Pittsburgh Sleep Quality Index (PSQI). We first divided the patients into two groups according to sleep quality (good sleep: PQSI < 5 and poor sleep: PSQI ≥ 5). Then, we analyzed routine sperm parameters (semen volume, sperm total motility, progressive motility, sperm concentration, total sperm number, and normal sperm morphology) and reproductive hormones (follicle-stimulating hormone, luteinizing hormone, estrogen, testosterone, and prolactin) of each group. Finally, we used multivariate linear regression analysis and Spearman correlation coefficients to examine the relationship between sleep quality (discrete variable or dichotomous variable) and sperm parameters, reproductive hormones.

RESULTS

A negative correlation was found between the general PSQI scores and several semen parameters: total motility (r= -0.187979, p< 0.001), progressive motility (r= -0.192902, p< 0.001), concentration (r= -0.167063, p< 0.001), total sperm number (r= -0.160008, p< 0.001), and normal sperm morphology (r= -0.124511, p< 0.001). However, there was no significant correlation between the semen volume, all reproductive hormones and the general PSQI scores. After adjusting for confounders, men with poor sleep had lower total motility (β= -9.287; 95% CI, -12.050, -6.523), progressive motility (β= -8.853; 95% CI, -11.526, -6.180), concentration (log scale, β= -0.131; 95% CI, -0.181, -0.082), total sperm number (log scale, β= -0.137; 95% CI, -0.189, -0.084), and normal sperm morphology (β= -1.195; 95% CI, -1.844, -0.547), but semen volume and all reproductive hormones were not markedly altered.

CONCLUSION

Poor sleep quality might be related to impaired semen quality, but we found no evidence that poor sleep quality affects reproductive hormones.

Molecular insights into ovary degeneration induced by environmental factors in female oriental river prawns Macrobrachium nipponense

The oriental river prawn, Macrobrachium nipponense, is an important breeding species in China. The ovary development of this prawn is regulated by the genetic factors and external environmental factors and has obvious seasonal regularity. However, the molecular mechanism of regulating ovary degradation in M. nipponense remains unclear. To address this issue, we performed transcriptome sequencing and gene expression analyses of eyestalks, cerebral ganglia (CG) and thoracic ganglia (TG) of female M. nipponense between the full ovary stage and degenerate ovary stage. Differentially expressed genes enrichment analysis results identified several important pathways such as "phototransduction-fly," "circadian rhythm-fly" and "steroid hormone biosynthesis secretion." In the period of ovarian degeneration, the expressions of Tim, Per2 and red pigment concentration hormone (RPCH) were significantly decreased in the eyestalk, CG and TG. And expression of 7 genes in the steroid synthesis pathway, including steryl-sulfatase, cytochrome P450 family 1 subfamily A polypeptide 1, estradiol 17β-dehydrogenase 2, glucuronosyltransferase, 3-oxo-5-alpha-steroid 4-dehydrogenase 1, estradiol 17-dehydrogenase 1 and estrone sulfotransferase was significantly decreased in the CG. Food and light signals affect the expression of clock genes and thereby decrease the expression of RPCH and the estradiol synthesis-related genes in the nervous system, which may be the main cause of ovarian degeneration in M. nipponense. The results will contribute to a better understanding of the molecular mechanisms of ovarian development regulation in crustaceans.

Host population related variations in circadian clock gene sequences and expression patterns in Chilo suppressalis

The rice stem borer, Chilo suppressalis Walker, is one of the most important global agricultural pests. C. suppressalis has distinct rice and water-oat host populations. Asynchrony in sexual activity is thought to be the main factor maintaining reproductive segregation between these populations, particularly the obvious difference in the circadian rhythm of female calling activity between populations. However, the mechanism responsible for this difference in the timing of female calling is poorly understood. The circadian clock is an essential regulator of daily behavioral rhythms in insects, including female calling. We investigated the variation in circadian clock genes of the rice and water-oat populations of C. suppressalis. We did this by comparing deduced amino acid sequences and the expression patterns of seven circadian clock genes (clock, cycle, period, timeless, timeout, cryptochrome1, and cryptochrome2) between females from each population. We found that the two populations had different variants of the timeout and cryptochrome1 genes and differed in the expression of period, timeless and timeout. This suggests that population-related variation in the circadian clock genes period, timeless, timeout and cryptochrome1 could be responsible for the different circadian rhythms of female calling in these host population of C. suppressalis. These results provide new insights into the molecular mechanisms underlying asynchronous sexual activity in insect populations and suggest new topics for future research on the origins and maintenance of population differentiation in insects.

Knockdown of timeless Disrupts the Circadian Behavioral Rhythms in Laodelphax striatellus (Hemiptera: Delphacidae)

Most living organisms developed the innate clock system to anticipate daily environmental changes and to enhance their chances of survival. timeless (tim) is a canonical clock gene. It has been extensively studied in Drosophila melanogaster (Diptera: Drosophilidae) as a key component of the endogenous circadian clock, but its role is largely unknown in some agriculture pests. Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae), an important rice pest, exhibits a robust locomotor rhythm. In the present study, we cloned tim gene (ls-tim) from L. striatellus and investigated its function in the regulation of behavioral rhythms. Quantitative real-time polymerase chain reaction revealed a circadian expression pattern of ls-tim under different light conditions with a trough in the photophase and a peak in the late scotophase. After the knockdown of ls-tim via RNA interference (RNAi), the adults showed an earlier onset of locomotor activity under light/dark cycles and became arrhythmic in constant darkness. ls-tim RNAi also abolished the timing of adult emergence that normally occurs in the early photophase. These results suggest that ls-tim is essential for the light-entrained circadian rhythms in L. striatellus and provide more insights into the endogenous clock network underlying the behavioral and physiological rhythms of this insect.

Sleep duration is associated with sperm chromatin integrity among young men in Chongqing, China

This study explores whether sleep duration is associated with sperm chromatin integrity. To do so, we conducted a three-phase panel study of 796 male volunteers from colleges in Chongqing (China) from 2013 to 2015. Sleep duration was measured using a modified Munich Chronotype Questionnaire. Sperm DNA integrity was examined via Sperm Chromatin Structure Assay and Comet assay. Setting 7-7.5 h day^-1 of sleep duration as a reference, either longer or shorter sleep duration was associated negatively with high DNA stainability (HDS) (P = 0.009), which reflected the immaturity of sperm chromatin. The volunteers with > 9.0 h day^-1 sleep and those with ≤ 6.5 h day^-1 sleep had 40.7 and 30.3% lower HDS than did volunteers with 7-7.5 h day^-1 sleep. No association was found between sleep duration and DNA fragmentation index or Comet assay parameters. This study suggests that sleep duration is associated with sperm chromatin integrity. Further studies are required to validate these findings and investigate the mechanism underlying this association.

Molecular cloning, characterization, and temporal expression of the clock genes period and timeless in the oriental river prawn Macrobrachium nipponense during female reproductive development

The circadian clock is crucial for sustaining rhythmic biochemical, physiological, and behavioral processes in living creatures. In this study, we isolated and characterized two circadian clock genes in Macrobrachium nipponense, period (Mnper) and timeless (Mntim). The complete Mnper cDNA measures 4283bp in length with an open reading frame encoding 1292 amino acids, including functional domains such as PER-ARNT-SIM (PAS), cytoplasmic localization domain (CLD), TIM interaction site (TIS), and nuclear localization signal (NLS). The deduced Mntim protein comprises1540 amino acids with functional domains such as PER interaction site (PIS), NLS, and CLD. Tissue distribution analyses showed that the two genes were highly expressed in the eyestalk and brain in both males and females, as well as being expressed in the ovary. The expression profiles of Mnper and Mntim were determined in the eyestalk, brain, and ovary under simulated breeding season and non-breeding season conditions. The expression profiles of both Mnper and Mntim appeared to be unaffected in the eyestalk. However, the expression of both genes exhibited significant seasonal variations in the brain, and thus we assumed the brain to be their functional location. The expression profiles under different simulated seasons and the variations during different ovarian stages indicate that both genes might be involved with female reproduction. Especially the mRNA levels in the brain varied greatly during these stages indicating that the clock function in the brain is closely related to ovarian development and female reproduction. And the reproductive roles of clock genes need to be elucidated.

Systemic RNA interference in locusts: reverse genetics and possibilities for locust pest control

RNA interference (RNAi) is a biological process triggered by double stranded (ds)RNA that results in sequence-dependent mRNA degradation. Because of its high specificity, this post-transcriptional gene silencing mechanism is a widely used tool for reverse genetics in several insect species. In particular, locusts possess a very robust and sensitive RNAi response that has already been exploited to investigate a diverse range of important physiological processes. These orthopteran insects constitute important model organisms in several areas of entomology, but they can also become voracious swarming pests that threaten the agricultural production in large parts of the world. In comparison to the widely applied chemical insecticides, the RNAi-technology could contribute to the development of a novel generation of insecticides, with high species-specificity. In this article, we discuss the potential of the RNAi-technology in loss of function studies in locusts, as well as to control locust populations.

Identification of the short neuropeptide F precursor in the desert locust: evidence for an inhibitory role of sNPF in the control of feeding

Peptides of the short neuropeptide F (sNPF) family have been shown to modulate feeding behavior in a wide variety of insect species. While these peptides stimulate feeding and food-searching behavior in Drosophila melanogaster and Apis mellifera, an opposite effect has recently been demonstrated in the desert locust, Schistocerca gregaria. In this study, we elaborate on these observations with the identification of the nucleotide sequence encoding the Schgr-sNPF precursor and the study of its role in the regulation of locust feeding behavior. We confirm that both Schgr-sNPF-like peptides, previously identified in mass spectrometric studies, are genuine precursor-encoded peptides. RNA interference mediated silencing of the Schgr-sNPF precursor transcript generates novel evidence for an inhibitory role of Schgr-sNPF in the regulation of feeding in S. gregaria. Furthermore, we show that starvation reduces the Schgr-sNPF precursor transcript level in the optic lobes, the primary visual centers of the locust brain. Our data indicate that Schgr-sNPF exerts an inhibitory effect on food uptake in the desert locust, which contrasts with effects of sNPF reported for several other insect species.

Effects of period RNAi on V-ATPase expression and rhythmic pH changes in the vas deferens of Spodoptera littoralis (Lepidoptera: Noctuidae)

Circadian clocks (oscillators) regulate multiple aspects of insect behaviour and physiology. The circadian system located in the male reproductive tract of Lepidoptera orchestrates rhythmic sperm release from testis and sperm maturation in the upper vas deferens (UVD). Our previous research on the cotton leafworm, Spodoptera littoralis, suggested rhythmic changes in the V-ATPase levels in the UVD epithelium, which correlated with rhythmic pH fluctuations in the UVD lumen. However, it was not known whether UVD cells contain clock mechanism that generates these daily fluctuations. In the current paper, we show circadian rhythm in the expression of clock gene period at the mRNA and protein level in the UVD epithelium. To determine the role of PER in V-ATPase and pH regulation, testes-UVD complexes were treated in vitro with double-stranded fragments of per mRNA (dsRNA). This treatment, which transiently lowered per mRNA and protein in the UVD, altered expression of V-ATPase c subunit. In addition, per RNAi caused a significant delay in the UVD lumen acidification. These data demonstrate that the UVD molecular oscillator involving the period gene plays an essential role in the regulation of rhythmic V-ATPase activity and periodic acidification of the UVD lumen.

Neuropeptide F regulates male reproductive processes in the desert locust, Schistocerca gregaria

Although Neuropeptide F (NPF) has been identified in different insect species, its function has mainly been studied in the fruit fly, Drosophila melanogaster, where it regulates diverse physiological processes, such as learning, stress responses and male courtship behavior. In locusts, only a truncated form of the "full-length" NPF (the biologically active "trNPF") has been isolated. This 9 AA peptide stimulates oocyte maturation, food intake and weight increase in adult desert locusts (Schistocerca gregaria [Forskål]). In this study, we investigated whether this peptide is also involved in the regulation of male reproductive physiology in this orthopteran species. Daily injections of trNPF in adult males resulted in proportionally heavier testes and seminal vesicles, while RNAi-mediated knockdown of the Schgr-NPF precursor transcript gave rise to proportionally lighter testes and seminal vesicles. Furthermore, adult males precociously displayed courtship behavior when injected daily with trNPF, while this behavior was inhibited or delayed by RNAi knockdown of the Schgr-NPF precursor transcript. In order to further analyze these effects of trNPF on male reproductive physiology, fertility of males was tested by analyzing progeny numbers following copulation with untreated females. In this way, we showed that daily trNPF injection in adult males resulted in a larger egg pod size and a higher percentage of hatched eggs per egg pod after copulation, while RNAi knockdown caused the opposite effects. Taken together, we provide clear evidence for a role of trNPF in the regulation of reproductive physiology in adult males of the desert locust, S. gregaria. Possible modes of action of trNPF in influencing these reproductive processes in male locusts are discussed.

RNA interference mortality points to noncircadian functions for the clock gene in the desert locust Schistocerca gregaria

One of the core genes in the circadian regulation network is clock (clk). By forming a heterodimer with CYCLE (CYC) that binds on an E-box in the promoter region, it induces the transcription of other elements in the circadian transcriptional feedback loops and different clock output genes. In contrast to other insects, a clk double-stranded RNA (dsRNA) treatment is lethal in adults and fifth instar nymphs of the desert locust, Schistocerca gregaria, in a dose-dependent manner. Clk knock down fifth instar nymphs are able to undergo their imaginal moult but, depending on the amount of dsRNA, it takes them longer than the controls to reach adulthood. As adults, clk knock down animals do not develop their fat body and ovaries like the control animals. Therefore, we tested the expression of different genes involved in energy metabolism and reproduction to see the effect of the clk RNA interference knock down. Surprisingly, the expression of the vitellogenin gene was up-regulated in the clk knock down females who did not appear to invest their energy in egg development. Taken together, our results point out that the clk gene in the desert locust has an additional function in development besides its established role in maintaining the circadian rhythms in the brain.