Unveiling the roles of Sertoli cells lineage differentiation in reproductive development and disorders: a review.

In mammals, gonadal somatic cell lineage differentiation determines the development of the bipotential gonad into either the ovary or testis. Sertoli cells, the only somatic cells in the spermatogenic tubules, support spermatogenesis during gonadal development. During embryonic Sertoli cell lineage differentiation, relevant genes, including WT1, GATA4, SRY, SOX9, AMH, PTGDS, SF1, and DMRT1, are expressed at specific times and in specific locations to ensure the correct differentiation of the embryo toward the male phenotype. The dysregulated development of Sertoli cells leads to gonadal malformations and male fertility disorders. Nevertheless, the molecular pathways underlying the embryonic origin of Sertoli cells remain elusive. By reviewing recent advances in research on embryonic Sertoli cell genesis and its key regulators, this review provides novel insights into sex determination in male mammals as well as the molecular mechanisms underlying the genealogical differentiation of Sertoli cells in the male reproductive ridge.

Control of two insect pests by expression of a mismatch corrected double-stranded RNA in plants.

RNA interference (RNAi) has emerged as an efficient technology for pest control by silencing the essential genes of targeted insects. Owing to its nucleotide sequence-guided working mechanism, RNAi has a high degree of species-specificity without impacts on non-target organisms. However, as plants are inevitably under threat by two or more insect pests in nature, the species-specific mode of RNAi-based technology restricts its wide application for pest control. In this study, we artificially designed an intermediate dsRNA (iACT) targeting two ß-Actin (ACT) genes of sap-sucking pests Bemisia tabaci and Myzus persicae by mutual correction of their mismatches. When expressing hairpin iACT (hpiACT) from tobacco nuclear genome, transgenic plants are well protected from both B. tabaci and M. persicae, either individually or simultaneously, as evidenced by reduced fecundity and suppressed ACT gene expression, whereas expression of hpRNA targeting BtACT or MpACT in transgenic tobacco plants could only confer specific resistance to either B. tabaci or M. persicae, respectively. In sum, our data provide a novel proof-of-concept that two different insect species could be simultaneously controlled by artificial synthesis of dsRNA with sequence optimization, which expands the range of transgenic RNAi methods for crop protection.

Structural insights into DNA N6-adenine methylation by the MTA1 complex.

N6-methyldeoxyadenine (6mA) has recently been reported as a prevalent DNA modification in eukaryotes. The Tetrahymena thermophila MTA1 complex consisting of four subunits, namely MTA1, MTA9, p1, and p2, is the first identified eukaryotic 6mA methyltransferase (MTase) complex. Unlike the prokaryotic 6mA MTases which have been biochemically and structurally characterized, the operation mode of the MTA1 complex remains largely elusive. Here, we report the cryogenic electron microscopy structures of the quaternary MTA1 complex in S-adenosyl methionine (SAM)-bound (2.6 Å) and S-adenosyl homocysteine (SAH)-bound (2.8 Å) states. Using an AI-empowered integrative approach based on AlphaFold prediction and chemical cross-linking mass spectrometry, we further modeled a near-complete structure of the quaternary complex. Coupled with biochemical characterization, we revealed that MTA1 serves as the catalytic core, MTA1, MTA9, and p1 likely accommodate the substrate DNA, and p2 may facilitate the stabilization of MTA1. These results together offer insights into the molecular mechanism underpinning methylation by the MTA1 complex and the potential diversification of MTases for N6-adenine methylation.

Transplastomic tomatoes expressing double-stranded RNA against a conserved gene are efficiently protected from multiple spider mites.

Spider mites are serious pests and have evolved significant resistance to many chemical pesticides, thus making their control challenging. Several insect pests can be combated by plastid-mediated RNA interference (PM-RNAi), but whether PM-RNAi can be utilized to control noninsect pests is unknown. Here, we show that three species of spider mites (Tetranychus evansi, Tetranychus truncatus, and Tetranychus cinnabarinus) take up plastid RNA upon feeding. We generated transplastomic tomato plants expressing double-stranded RNA (dsRNA) targeted against a conserved region of the spider mite ß-Actin mRNA. Transplastomic plants exhibited high levels of resistance to all three spider mite species, as evidenced by increased mortality and suppression of target gene expression. Notably, transplastomic plants induced a more robust RNAi response, caused higher mortality, and were overall better protected from spider mites than dsRNA-expressing nuclear transgenic plants. Our data demonstrate the potential of PM-RNAi as an efficient pest control measure for spider mites and extend the application range of the technology to noninsect pests.

Control of a sap-sucking insect pest by plastid-mediated RNA interference.

Expression of double-stranded RNAs in plastids offers great potential for the efficient control of chewing insects. However, many insect pests do not consume plant tissue but rather feed on the host plant by sucking sap from the vascular system. Whether or not plastid-mediated RNA interference (RNAi) can be employed to control sap-sucking insects is unknown. Here, we show that five species of sap-sucking hemipteran insects acquire plastid RNA upon feeding on plants. We generated both nuclear transgenic and transplastomic tobacco plants expressing double-stranded RNAs targeting the MpDhc64C gene, a newly identified efficient target gene of RNAi whose silencing causes lethality to the green peach aphid Myzus persicae. In a whole-plant bioassay, transplastomic plants exhibited significant resistance to aphids, as evidenced by reduced insect survival, impaired fecundity, and decreased weight of survivors. The protective effect was comparable with that conferred by the best-performing nuclear transgenic plants. We found that the proportion of aphids on mature leaves of transplastomic plants was significantly lower compared with that of nuclear transgenic plants. When aphids were allowed to infest only the mature leaves, transplastomic plants grew significantly faster and were overall better protected from the pest compared with nuclear transgenic plants. When monitored by electrical-penetration-graph analyses and aphid avoidance response experiments, the insects displayed remarkable alterations in feeding behavior, which was different in nuclear transgenic and transplastomic plants, likely reflecting specific avoidance strategies to toxic RNA molecules. Taken together, our study demonstrates that plastid-mediated RNAi provides an efficient strategy for controlling at least some sap-sucking insect pests, even though there is most likely no or only very little chloroplast RNA in the sap.

Inaccessibility to double-stranded RNAs in plastids restricts RNA interference in Bemisia tabaci (whitefly).

BACKGROUND: RNA interference (RNAi) has emerged as a promising technology for insect pest control. Because of the accumulation of high levels of long double-stranded RNAs (dsRNAs) in plastids, it was previously shown that expression of dsRNAs from plastid genome led to higher mortality of some insect pests with chewing mouthparts than dsRNAs expression from nuclear genome. However, whether plastid-expressed dsRNAs have effects on phloem sap-sucking pests is unknown. In this study, we compared the RNAi effects of nuclear transgenic and transplastomic plants on the whitefly Bemisia tabaci, a serious sap-sucking pest. RESULTS: Nuclear transgenic and transplastomic tobacco plants were developed for the expression of dsRNA against BtACTB gene of Bemisia tabaci, respectively. Feeding nuclear transgenic plants to Bemisia tabaci resulted in reduced gene expression of BtACTB and survival rate, and impaired fecundity of Bemisia tabaci. We did not observe any effects of transplastomic plants on Bemisia tabaci fitness. Furthermore, we found that the inability of B. tabaci to obtain dsRNAs from plastids might restrict its RNAi responses. CONCLUSION: Our study indicated that the expression of dsRNAs in nuclear transgenic plants was more effective than that in transplastomic plants for the control of Bemisia tabaci. The inaccessibility of Bemisia tabaci to plastids contributes to the inefficiency of plastid-mediated RNAi. Our findings are of great significance to future optimization of transgenically delivered RNAi approaches for efficient controlling of sap-sucking pests. © 2020 Society of Chemical Industry.

High-performance liquid chromatography combined with mass spectrum analysis for identifying the antifatigue components in Acanthopanax senticosus Harms.

The roots of Acanthopanax senticosus (Rupr. et Maxim.) Harm were obtained for the acquisition of the crude extractives to isolate the 19 components by means of preliminary extraction and isolation. High-performance liquid chromatography followed by primary and secondary mass spectrum analysis (HPLC/MS/MS) was employed to identify the antifatigue components from the extracts of the plant with reference to the literature. Good isolation results were achieved and several known and unknown chemical compounds were identified, for instance, in one sample (No. 11) 5 known components were detected along with 6 unknown compounds with relative molecular mass of 302, 318, 346, 354, 390, and 406, respectively.