An at-leg pellet and associated Penicillium sp. provide multiple protections to mealybugs.

Beneficial fungi are well known for their contribution to insects' adaptation to diverse habitats. However, where insect-associated fungi reside and the underlying mechanisms of insect-fungi interaction are not well understood. Here, we show a pellet-like structure on the legs of mealybugs, a group of economically important insect pests. This at-leg pellet, formed by mealybugs feeding on tomato but not by those on cotton, potato, or eggplant, originates jointly from host secretions and mealybug waxy filaments. A fungal strain, Penicillium citrinum, is present in the pellets and it colonizes honeydew. P. citrinum can inhibit mealybug fungal pathogens and is highly competitive in honeydew. Compounds within the pellets also have inhibitory activity against mealybug pathogens. Further bioassays suggest that at-leg pellets can improve the survival rate of Phenacoccus solenopsis under pathogen pressure, increase their sucking frequency, and decrease the defense response of host plants. Our study presents evidences on how a fungi-associated at-leg pellet provides multiple protections for mealybugs through suppressing pathogens and host defense, providing new insights into complex insect × fungi × plant interactions and their coevolution.

Endosymbiont Tremblaya phenacola influences the reproduction of cotton mealybugs by regulating the mechanistic target of rapamycin pathway.

The intricate evolutionary dynamics of endosymbiotic relationships result in unique characteristics among the genomes of symbionts, which profoundly influence host insect phenotypes. Here, we investigated an endosymbiotic system in Phenacoccus solenopsis, a notorious pest of the subfamily Phenacoccinae. The endosymbiont, "Candidatus Tremblaya phenacola" (T. phenacola PSOL), persisted throughout the complete life cycle of female hosts and was more active during oviposition, whereas there was a significant decline in abundance after pupation in males. Genome sequencing yielded an endosymbiont genome of 221.1 kb in size, comprising seven contigs and originating from a chimeric arrangement between betaproteobacteria and gammaproteobacteria. A comprehensive analysis of amino acid metabolic pathways demonstrated complementarity between the host and endosymbiont metabolism. Elimination of T. phenacola PSOL through antibiotic treatment significantly decreased P. solenopsis fecundity. Weighted gene coexpression network analysis demonstrated a correlation between genes associated with essential amino acid synthesis and those associated with host meiosis and oocyte maturation. Moreover, altering endosymbiont abundance activated the host mechanistic target of rapamycin pathway, suggesting that changes in the amino acid abundance affected the host reproductive capabilities via this signal pathway. Taken together, these findings demonstrate a mechanism by which the endosymbiont T. phenacola PSOL contributed to high fecundity in P. solenopsis and provide new insights into nutritional compensation and coevolution of the endosymbiotic system.

Construction of Type-II Heterojunctions in Crystalline Carbon Nitride for Efficient Photocatalytic H2 Evolution.

As an encouraging photocatalyst, crystalline carbon nitride (CCN) exhibits unsatisfactory photocatalytic activity and stability due to its rapid recombination of photo-generative carriers. Herein, high-crystalline g-C3N4 was prepared, including CCN obtained in KCl (K-CCN), LiCl-KCl mixture (Li/K-CCN), and LiCl-NaCl-KCl mixture (Li/Na/K-CCN), via the molten salt strategy using pre-prepared bulk carbon nitride (BCN) as a precursor. The obtained BCN sample was formed by heptazine-based units, which convert into triazine-based units for K-CCN. Heptazine and triazine are two isotypes that co-exist in the Li/K-CCN and Li/Na/K-CCN samples. Compared with BCN and other CCN samples, the as-prepared Li/Na/K-CCN sample exhibited the optimal photocatalytic hydrogen evolution rates (3.38 mmol·g-1·h-1 under simulated sunlight and 2.25 mmol·g-1·h-1 under visible light) and the highest apparent quantum yield (10.97%). The improved photocatalytic performance of the Li/Na/K-CCN sample is mainly attributed to the construction of type-II heterojunction and the institution of the built-in electric field between triazine-based CCN and heptazine-based BCN. This work provides a new strategy for the structural optimization and heterostructure construction of crystalline carbon nitride photocatalysts.

Oxygen Vacancy Induced Atom-Level Interface in Z-Scheme SnO2/SnNb2O6 Heterojunctions for Robust Solar-Driven CO2 Conversion.

The modulation of Z-scheme charge transfer is essential for efficient heterostructure toward photocatalytic CO2 reduction. However, constructing a compact hetero-interface favoring the Z-scheme charge transfer remains a great challenge. In this work, an interfacial Nb-O-Sn bond and built-in electric field-modulated Z-scheme Ov-SnO2/SnNb2O6 heterojunction was prepared for efficient photocatalytic CO2 conversion. Systematic investigations reveal that an atomic-level interface is constructed in the Ov-SnO2/SnNb2O6 heterojunction. Under simulated sunlight irradiation, the obtained Ov-SnO2/SnNb2O6 photocatalyst exhibits a high CO evolution rate of 147.4 µmol h-1 g-1 from CO2 reduction, which is around 3-fold and 3.3-fold of SnO2/SnNb2O6 composite and pristine SnNb2O6, respectively, and favorable cyclability by retaining 95.8% rate retention after five consecutive tests. As determined by electron paramagnetic resonance spectra, in situ Fourier transform infrared spectra, and density functional theory calculations, Nb-O-Sn bonds and built-in electric field induced by the addition of oxygen vacancies jointly accelerate the Z-scheme charge transfer for enhanced photocatalytic performance. This work provides a promising route for consciously modulating Z-scheme charge transfer by atomic-level interface engineering to boost photocatalytic performance.

Machine learning to analyze the factors influencing myopia in students of different school periods.

Purpose: We aim to develop myopia classification models based on machine learning algorithms for each schooling period, and further analyze the similarities and differences in the factors influencing myopia in each school period based on each model. Design: Retrospective cross-sectional study. Participants: We collected visual acuity, behavioral, environmental, and genetic data from 7,472 students in 21 primary and secondary schools (grades 1-12) in Jiamusi, Heilongjiang Province, using visual acuity screening and questionnaires. Methods: Machine learning algorithms were used to construct myopia classification models for students at the whole schooling period, primary school, junior high school, and senior high school period, and to rank the importance of features in each model. Results: The main influencing factors for students differ by school section, The optimal machine learning model for the whole schooling period was Random Forest (AUC = 0.752), with the top three influencing factors being age, myopic grade of the mother, and Whether myopia requires glasses. The optimal model for the primary school period was a Random Forest (AUC = 0.710), with the top three influences being the myopic grade of the mother, age, and extracurricular tutorials weekly. The Junior high school period was an Support Vector Machine (SVM; AUC = 0.672), and the top three influencing factors were gender, extracurricular tutorial subjects weekly, and whether can you do the "three ones" when reading and writing. The senior high school period was an XGboost (AUC = 0.722), and the top three influencing factors were the need for spectacles for myopia, average daily time spent outdoors, and the myopic grade of the mother. Conclusion: Factors such as genetics and eye use behavior all play an essential role in students' myopia, but there are differences between school periods, with those in the lower levels focusing on genetics and those in the higher levels focusing on behavior, but both play an essential role in myopia.

Association of a single amino acid replacement with dorsal pigmentation in a lizard from the Qinghai-Tibetan Plateau.

Reptiles can evolve adaptive colors in different environments, but relatively little is known about the genetic mechanisms. Here, we identified the MC1R gene and its association with intraspecific color variation in the lizard Phrynocephalus erythrurus. Analysis of the MC1R sequence in 143 individuals from dark South Qiangtang Plateau (SQP) and light North Qiangtang plateau (NQP) populations, revealed two amino acid sites that showed significant differences in frequency between two areas. One SNP, corresponding to Glu183Lys residue, was found to be a highly significant outlier and differentially fixed for SQP and NQP populations. This residue is located in an extracellular area in the second small extracellular loop within the secondary structure of MC1R, which represents an "attachment pocket" part of the 3D structure. Cytological expression of MC1R alleles with the Glu183Lys replacement showed a 39 % increase in intracellular agonist-induced cyclic AMP levels and a 23.18 % greater cell surface expression of MC1R protein in the SQP relative to the NQP allele. Further in silico 3D modeling and in vitro binding experiments indicated a higher MC1R-α-MSH binding for the SQP allele, and elevated melanin synthesis. We provide an overview of how a single amino acid replacement leads to fundamental changes in MC1R function, and hence shapes variation in dorsal pigmentation in lizards from different environments.

Weakened Crystalline SnNb2 O6 for Enhanced Performance in Photocatalytic H2 Production and CO2 Reduction.

Low crystalline photocatalysts with unsaturated active sites, such as oxygen vacancy (Ov ), is reported to exhibit enhanced adsorption and activation of oxygen-containing small molecules, such as H2 O and CO2 , thus boosting the activity in photocatalytic H2 evolution and CO2 reduction. However, numerous low-crystalline photocatalysts show unsatisfactory stability due to the easily repaired surface Ov . Herein, three SnNb2 O6 with different crystallinity were prepared by hydrothermal approach with similar precursors. Compared with bulk SnNb2 O6 and ultra-thin layered SnNb2 O6 , low-crystalline SnNb2 O6 (SNA) exhibits optimal visible-light-driven evolution rates of H2 (86.04 µmol g-1 h-1 ) and CO from CO2 (71.97 µmol g-1 h-1 ), which is mainly ascribed to the fast separation of the photogenerated carriers and enhanced photoreduction power caused by the surface Ov . More importantly, the sharp decrease of photocatalytic activity of SNA after seven cycles is well restored by the hydrothermal treatment of recycled SNA, ascribed to the reactivated surface Ov with the recovered low-crystalline structure. These works thus offer a promising strategy for developing low-crystalline and amorphous photocatalysts with high activity and stability.

Gender differences in myopia prevalence among Han students aged 7 to 18 years in China during 2005-2019 / 中国学校卫生

Objective@#To investigate gender differences regarding changes of myopia rates among Han Chinese students aged 7-18 years in China, and to provide a scientific basis for precise myopia prevention and control.@*Methods@#The visual acuity data of 871 112 students aged 7-18 years from four national student physical fitness and health surveys in 2005, 2010, 2014 and 2019 were selected to analyze gender differences in myopia rates and myopia rates among male and female students in each age group.@*Results@#The overall myopia rate of students aged 7-18 years in China increased from 2005 to 2019( χ 2=7 265.06, P <0.01), and the myopia rate increased from 47.9%(2005) to 60.1% (2019). Gender differences in myopia rates among students trended to decrease( χ 2=72.24, P <0.01), and showed an inverted "U shaped" distribution from south to north, decreasing first and then increasing.@*Conclusion@#The problem of myopia in children and adolescents cannot be ignored, and the difference in myopia rates between male and female students should be taken into account, precise prevention and control of myopia accurately according to gender.

Fatty acyl-CoA reductase influences wax biosynthesis in the cotton mealybug, Phenacoccus solenopsis Tinsley.

Mealybugs are highly aggressive to a diversity of plants. The waxy layer covering the outermost part of the integument is an important protective defense of these pests. However, the molecular mechanisms underlying wax biosynthesis in mealybugs remain largely unknown. Here, we analyzed multi-omics data on wax biosynthesis by the cotton mealybug, Phenacoccus solenopsis Tinsley, and found that a fatty acyl-CoA reductase (PsFAR) gene, which was highly expressed in the fat bodies of female mealybugs, contributed to wax biosynthesis by regulating the production of the dominant chemical components of wax, cuticular hydrocarbons (CHCs). RNA interference (RNAi) against PsFAR by dsRNA microinjection and allowing mealybugs to feed on transgenic tobacco expressing target dsRNA resulted in a reduction of CHC contents in the waxy layer, and an increase in mealybug mortality under desiccation and deltamethrin treatments. In conclusion, PsFAR plays crucial roles in the wax biosynthesis of mealybugs, thereby contributing to their adaptation to water loss and insecticide stress.

Elevation as a selective force on mitochondrial respiratory chain complexes of the Phrynocephalus lizards in the Tibetan plateau.

Animals living in extremely high elevations have to adapt to low temperatures and low oxygen availability (hypoxia), but the underlying genetic mechanisms associated with these adaptations are still unclear. The mitochondrial respiratory chain can provide >95% of the ATP in animal cells, and its efficiency is influenced by temperature and oxygen availability. Therefore, the respiratory chain complexes (RCCs) could be important molecular targets for positive selection associated with respiratory adaptation in high-altitude environments. Here, we investigated positive selection in 5 RCCs and their assembly factors by analyzing sequences of 106 genes obtained through RNA-seq of all 15 Chinese Phrynocephalus lizard species, which are distributed from lowlands to the Tibetan plateau (average elevation >4,500 m). Our results indicate that evidence of positive selection on RCC genes is not significantly different from assembly factors, and we found no difference in selective pressures among the 5 complexes. We specifically looked for positive selection in lineages where changes in habitat elevation happened. The group of lineages evolving from low to high altitude show stronger signals of positive selection than lineages evolving from high to low elevations. Lineages evolving from low to high elevation also have more shared codons under positive selection, though the changes are not equivalent at the amino acid level. This study advances our understanding of the genetic basis of animal respiratory metabolism evolution in extreme high environments and provides candidate genes for further confirmation with functional analyses.

Dorsal Pigmentation and Its Association with Functional Variation in MC1R in a Lizard from Different Elevations on the Qinghai-Tibetan Plateau.

Identification of the role of the MC1R gene has provided major insights into variation in skin pigmentation in several organisms, including humans, but the evolutionary genetics of this variation is less well established. Variation in this gene and its relationship with degree of melanism was analyzed in one of the world's highest-elevation lizards, Phrynocephalus theobaldi from the Qinghai-Tibetan Plateau. Individuals from the low-elevation group were shown to have darker dorsal pigmentation than individuals from a high-elevation group. The existence of climatic variation across these elevations was quantified, with lower elevations exhibiting higher air pressure, temperatures, and humidity, but less wind and insolation. Analysis of the MC1R gene in 214 individuals revealed amino acid differences at five sites between intraspecific sister lineages from different elevations, with two sites showing distinct fixed residues at low elevations. Three of the four single-nucleotide polymorphisms that underpinned these amino acid differences were highly significant outliers, relative to the generalized MC1R population structuring, suggestive of selection. Transfection of cells with an MC1R allele from a lighter high-elevation population caused a 43% reduction in agonist-induced cyclic AMP accumulation, and hence lowered melanin synthesis, relative to transfection with an allele from a darker low-elevation population. The high-elevation allele led to less efficient integration of the MC1R protein into melanocyte membranes. Our study identifies variation in the degree of melanism that can be explained by four or fewer MC1R substitutions. We establish a functional link between these substitutions and melanin synthesis and demonstrate elevation-associated shifts in their frequencies.

A chromosome-level genome assembly provides new insights into paternal genome elimination in the cotton mealybug Phenacoccus solenopsis.

Mealybugs (Hemiptera: Pseudococcidae) are economically important agricultural pests with several compelling biological phenomena including paternal genome elimination (PGE). However, limited high-quality genome assemblies of mealybugs hinder a full understanding of this striking and unusual biological phenomenon. Here, we generated a chromosome-level genome assembly of cotton mealybug, Phenacoccus solenopsis, by combining Illumina short reads, PacBio long reads and Hi-C scaffolding. The assembled genome was 292.54 Mb with a contig N50 of 489.8 kb and a scaffold N50 of 49.0 Mb. Hi-C scaffolding assigned 84.42% of the bases to five chromosomes. A total of 110.75 Mb (37.9%) repeat sequences and 11,880 protein-coding genes were predicted. The completeness of the genome assembly was estimated to be 95.5% based on BUSCO genes. In addition, 27,086 (95.3%) full-length PacBio transcripts were uniquely mapped to the assembled scaffolds, suggesting the high quality of the genome assembly. We showed that cotton mealybugs lack differentiated sex chromosomes by analysing genome resequencing data of males and females. DAPI staining confirmed that one chromosome set in males becomes heterochromatin at an early embryo stage. Chromatin immunoprecipitation assays with sequencing analysis demonstrated that the epigenetic modifications H3K9me3 and H3K27me3 are distributed across the whole genome in males, suggesting that these two modifications might be involved in maintaining heterochromatin status. Both markers were more likely to be distributed in repeat regions, while H3K27me3 had higher overall enrichment. Our results provide a valuable genomic resource and shed new light on the genomic and epigenetic basis of PGE in cotton mealybugs.

Effects of substrate color on intraspecific body color variation in the toad-headed lizard, Phrynocephalus versicolor.

Diversity in animal coloration is generally associated with adaptation to their living habitats, ranging from territorial display and sexual selection to predation or predation avoidance, and thermoregulation. However, the mechanism underlying color variation in toad-headed Phrynocephalus lizards remains poorly understood. In this study, we investigated the population color variation of Phrynocephalus versicolor. We found that lizards distributed in dark substrate have darker dorsal coloration (melanic lizards) than populations living in light substrates. This characteristic may improve their camouflage effectiveness. A reciprocal substrate translocation experiment was conducted to clarify the potential role of morphological adaptation and physiological plasticity of this variation. Spectrometry technology and digital photography were used to quantify the color variation of the above-mentioned melanic and nonmelanic P. versicolor populations and their native substrate. Additionally, substrate color preference in both populations was investigated with choice experiments. Our results indicate that the melanic and nonmelanic populations with remarkable habitat color difference were significantly different on measured reflectance, luminance, and RGB values. Twenty-four hours, 30 days, and 60 days of substrate translocation treatment had little effects on dorsal color change. We also found that melanic lizards choose to live in dark substrate, while nonmelanic lizards have no preference for substrate color. In conclusion, our results support that the dorsal coloration of P. versicolor, associated with substrate color, is likely a morphological adaptation rather than phenotypic plasticity.

Male mating and female postmating performances in cotton mealybug (Hemiptera: Pseudococcidae): effects of female density.

For insects, female density is closely related to reproductive output. However, little is known about the effects of female density on male mating and female postmating performances. Here, we explored the effects of female density in cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), an invasive, rapidly spreading pest in Asia damaging multiple crops and horticultural plants. Using USB digital microscopes, we investigated the frequency, duration, and intervals of mating for males that were individually supplied with 1, 5, 10, and 15 females. We also evaluated the reproduction of mated females and the sex ratio of their offspring. As the female density increased, males mated with more females while substantially shortening mating intervals. Mating occurred actively at the densities of 10 and 15 females, where males mated four times on average, and some mated 6-9 times. However, mating duration and the observed reproductive parameters of females (preoviposition period, overall period from formation of ovisacs to female death, fecundity, and offspring sex ratio) did not differ significantly with female density. A weak trade-off existed between males' mating frequency and longevity, but there was no relationship between females' fecundity and longevity. In conclusion, despite their short lifespan, P. solenopsis males have a high mating capacity, and their mating frequency and intervals can be significantly affected by female density. In contrast, female density has little influence on females' postmating performance. Our findings indicate the significance of the reproductive biology and life history strategies for rapid establishment and population development of mealybugs in newly invaded regions.

Evolutionary analysis of mitochondrially encoded proteins of toad-headed lizards, Phrynocephalus, along an altitudinal gradient.

BACKGROUND: Animals living at high altitude must adapt to environments with hypoxia and low temperatures, but relatively little is known about underlying genetic changes. Toad-headed lizards of the genus Phrynocephalus cover a broad altitudinal gradient of over 4000 m and are useful models for studies of such adaptive responses. In one of the first studies to have considered selection on mitochondrial protein-coding regions in an ectothermic group distributed over such a wide range of environments, we analysed nineteen complete mitochondrial genomes from all Chinese Phrynocephalus (including eight genomes sequenced for the first time). Initial analyses used site and branch-site model (program: PAML) approaches to examine nonsynonymous: synonymous substitution rates across the mtDNA tree. RESULTS: Ten positively selected sites were discovered, nine of which corresponded to subunits ND2, ND3, ND4, ND5, and ND6 within the respiratory chain enzyme mitochondrial Complex I (NADH Coenzyme Q oxidoreductase). Four of these sites showed evidence of general long-term selection across the group while the remainder showed evidence of episodic selection across different branches of the tree. Some of these branches corresponded to increases in altitude and/or latitude. Analyses of physicochemical changes in protein structures revealed that residue changes at sites that were under selection corresponded to major functional differences. Analyses of coevolution point to coevolution of selected sites within the ND4 subunit, with key sites associated with proton translocation across the mitochondrial membrane. CONCLUSIONS: Our results identify mitochondrial Complex I as a target for environment-mediated selection in this group of lizards, a complex that frequently appears to be under selection in other organisms. This makes these lizards good candidates for more detailed future studies of molecular evolution.

The complete mitochondrial genome of the subspecies, Phrynocephalus erythrurus parva (Reptilia, Squamata, Agamidae), a toad-headed lizard dwell at highest elevations of any reptile in the world.

The complete mitochondrial genome was sequenced from the toad-headed viviparous lizard subspecies, Phrynocephalus erythrurus parva, which occupies the highest regions of any reptile on the earth. The mitogenome sequence was 16,431 bp in size, with the overall base composition of H-strand is T: 26.06%, C: 25.14%, A: 36.45%, G: 12.35%. It consists of 13 protein coding, 22 tRNA, 2 rRNA genes and 3 control regions, and its gene order and gene content were identical with the published congeneric mitogenomes of other Phrynocephalus, except for the small protion between tRNA-Pro and tRNA-Phe.

The complete mitochondrial genome of an agama, Phrynocephalus putjatia (Reptilia, Squamata, Agamidae).

The complete mitochondrial genome was sequenced from the toad-headed viviparous lizard, Phrynocephalus putjatia. The mitogenome was 16,283 bp in length; it contained 13 protein coding, 22 tRNA, 2 rRNA genes and 2 control regions. The gene order and compositions were identical with all published congeneric mitogenomes for the fragment between 12 s RNA and tRNA-Thr, but with some differences for the remaining sequences including CR, tRNA-Pro and tRNA-Phe. The characteristics of the mitogenome was analyzed and discussed in detail.