Cerebral dominance representation of directed connectivity within and between left-right hemispheres and frontal-posterior lobes in mild cognitive impairment.

Electroencephalography can assess connectivity between brain hemispheres, potentially influencing cognitive functions. Much of the existing electroencephalography research primarily focuses on undirected connectivity, leaving uncertainties about directed connectivity alterations between left-right brain hemispheres or frontal-posterior lobes in mild cognitive impairment. We analyzed resting-state electroencephalography data from 34 mild cognitive impairment individuals and 23 normal controls using directed transfer function and graph theory for directed network analysis. Concerning the dominance within left-right hemispheres or frontal-posterior lobes, the mild cognitive impairment group exhibited decreased connectivity within the frontal compared with posterior brain regions in the delta and theta bands. Regarding the dominance between the brain hemispheres or lobes, the mild cognitive impairment group showed reduced connectivity from the posterior to the frontal regions versus the reverse direction in the same bands. Among all participants, the intra-lobe frontal-posterior dominance correlated positively with executive function in the delta and alpha bands. Inter-lobe dominance between frontal and posterior regions also positively correlated with executive function, attention, and language in the delta band. Additionally, interhemispheric dominance between the left and right hemispheres positively correlated with attention in delta and theta bands. These findings suggest altered cerebral dominance in mild cognitive impairment, potentially serving as electrophysiological markers for neurocognitive disorders.

Female lizards (Eremias argus) reverse Bergmann's rule across altitude.

The evolution of body size within and among species is predicted to be influenced by multifarious environmental factors. However, the specific drivers of body size variation have remained difficult to understand because of the wide range of proximate factors that covary with ectotherm body sizes across populations with varying local environmental conditions. Here, we used female Eremias argus lizards collected from different populations across their wide range in China, and constructed linear mixed models to assess how climatic conditions and/or available resources at different altitudes shape the geographical patterns of lizard body size across altitude. Lizard populations showed significant differences in body size across altitudes. Furthermore, we found that climatic and seasonal changes along the altitudinal gradient also explained variations in body size among populations. Specifically, body size decreased with colder and drier environmental conditions at high altitudes, reversing Bergmann's rule. Limited resources at high altitudes, measured by the low vegetative index, may also constrain body size. Therefore, our study demonstrates that multifarious environmental factors could strongly influence the intraspecific variation in organisms' body size.

The eggshell-matrix protein gene OC-17 is functionally lost in the viviparous Chinese crocodile lizard.

Thickness reduction or loss of the calcareous eggshell is one of major phenotypic changes in the transition from oviparity to viviparity. Whether the reduction of eggshells in viviparous squamates is associated with specific gene losses is unknown. Taking advantage of a newly generated high-quality genome of the viviparous Chinese crocodile lizard (Shinisaurus crocodilurus), we found that ovocleidin-17 gene (OC-17), which encodes an eggshell matrix protein that is essential for calcium deposition in eggshells, is not intact in the crocodile lizard genome. Only OC-17 transcript fragments were found in the oviduct transcriptome, and no OC-17 peptides were identified in the eggshell proteome of crocodile lizards. In contrast, OC-17 was present in the eggshells of the oviparous Mongolia racerunner (Eremias argus). Although the loss of OC-17 is not common in viviparous species, viviparous squamates show fewer intact eggshell-specific proteins than oviparous squamates. Our study implies that functional loss of eggshell-matrix protein genes may be involved in the reduction of eggshells during the transition from oviparity to viviparity in the crocodile lizard.

Ancient Demographics Determine the Effectiveness of Genetic Purging in Endangered Lizards.

The purging of deleterious alleles has been hypothesized to mitigate inbreeding depression, but its effectiveness in endangered species remains debatable. To understand how deleterious alleles are purged during population contractions, we analyzed genomes of the endangered Chinese crocodile lizard (Shinisaurus crocodilurus), which is the only surviving species of its family and currently isolated into small populations. Population genomic analyses revealed four genetically distinct conservation units and sharp declines in both effective population size and genetic diversity. By comparing the relative genetic load across populations and conducting genomic simulations, we discovered that seriously deleterious alleles were effectively purged during population contractions in this relict species, although inbreeding generally enhanced the genetic burden. However, despite with the initial purging, our simulations also predicted that seriously deleterious alleles will gradually accumulate under prolonged bottlenecking. Therefore, we emphasize the importance of maintaining a minimum population capacity and increasing the functional genetic diversity in conservation efforts to preserve populations of the crocodile lizard and other endangered species.

Complete mitochondrial genome of the Alpine Metacarpal-tubercled Toad Leptobrachella alpina (Amphibia, Anura, Megophryidae).

The complete mitochondrial genome of the Leptobrachella alpina Fei, Ye, and Li 1990, was assembled for the first time. The mitogenome of this species was 17,763 bp in length, containing 13 protein-coding genes, two ribosomal RNA genes (12S rRNA and 16S rRNA), 22 transfer RNA genes (tRNA), and a non-coding control region (D-loop). The base content of the mitogenome was that A, T, G, and C occupied 28.5%, 30.8%, 15.1%, and 25.6%, respectively. The phylogenetic analysis was conducted based on 17 complete mitogenome sequences of the family Megophryidae by the Bayesian inference approach. The phylogenetic tree suggested that Leptobrachium and Oreolalax clustered into a clade and formed a sister group with Leptobrachella. This work is critical for the further genetic research and conservation of this species.

Captivity Influences Gut Microbiota in Crocodile Lizards (Shinisaurus crocodilurus).

Captivity is an important measure for conservation of an endangered species, and it is becoming a hot topic in conservation biology, which integrates gut microbiota and endangered species management in captivity. As an ancient reptile, the crocodile lizard (Shinisaurus crocodilurus) is facing extreme danger of extinction, resulting in great significance to species conservation in the reserve. Thus, it is critical to understand the differences in gut microbiota composition between captive and wild populations, as it could provide fundamental information for conservative management of crocodile lizards. Here, fecal samples of crocodile lizards were collected from two wild and one captive populations with different ages (i.e., juveniles and adults) and were analyzed for microbiota composition by 16S ribosomal RNA (rRNA) gene amplicon sequencing. This study showed that the lizard gut microbiota was mainly composed of Firmicutes and Proteobacteria. The gut microbiota composition of crocodile lizard did not differ between juveniles and adults, as well as between two wild populations. Interestingly, captivity increased community richness and influenced community structures of gut microbiota in crocodile lizards, compared with wild congeners. This was indicated by higher abundances of the genera Epulopiscium and Glutamicibacter. These increases might be induced by complex integration of simple food resources or human contact in captivity. The gut microbiota functions of crocodile lizards are primarily enriched in metabolism, environmental information processing, genetic information processing, and cellular processes based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. This study provides fundamental information about the gut microbiota of crocodile lizards in wild and captive populations. In the future, exploring the relationship among diet, gut microbiota, and host health is necessary for providing animal conservation strategies.

The complete mitochondrial genome of Oreolalax lichuanensis (Amphibia, Anura, Megophryidae).

The complete mitochondrial genome of the Oreolalax lichuanensis was determined. It is a circular molecule of 17 702 bp in size and consists of 13 protein-coding genes, 23 tRNA genes, two rRNA genes and a control region (D-loop). The base composition on light strand was 28.0% A, 32.2% T, 24.9% C and 14.9% G. Compared with most other vertebrates, this mitogenome appear a tandem duplication of tRNA-Met gene. This study will facilitate the further research of the population genetics of this species and systematic study of the genus Oreolalax.

The complete mitochondrial genome of Oreolalax major (Anura: Megophryidae).

The complete mitochondrial genome of a frog species Oreolalax major is determined. This mitogenome length is 17 431 bp, containing 13 protein-coding genes, two rRNA genes, 23 tRNA genes and a control region (D-loop). Compared with most other vertebrates, this mitogenome appears a tandem duplication of tRNAMet gene. The tRNATrp gene of Oreolalax major translocates from the "WANCY" tRNA cluster to upstream of D-loop. As the first report of the mitogenome sequence from the genus Oreolalax, it will provide fundamental data for further research of phylogeny and biogeography with this genus.

Complete mitochondrial genome of the Leishan moustache toad, Vibrissaphora leishanensis (Anura: Megophryidae).

The complete mitogenome of Leishan moustache toad, Vibrissaphora leishanensis, is determined. The mitogenome size is 17,485 bp, containing 13 protein-coding genes, 2 rRNA genes, 23 tRNA genes and a control region (D-loop). The base composition of the whole genome is 28.1% A, 32.6% T, 24.4% C and 14.8% G. As observed in this genus before, this mitogenome also appears a tandem duplication of tRNAMet gene. This study will provide fundamental data for further research to resolve population genetics of this species and systematic problems of the genus Vibrissaphora.

The complete mitochondrial genome of Kaloula rugifera (Amphibia, Anura, Microhylidae).

We determined the complete mitochondrial genome of Kaloula rugifera in this work. The mitogenome was 17,073 bp in length, containing 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and a control region (D-loop). The base composition of the light strand was 29.7% A, 30.4% T, 25.7% C and 14.2% G. The gene order and contents of it is identical to most amphibian mitogenome. All protein-coding genes began with ATG as start codon except ND1 gene beginning with GTG and COI gene beginning with ATA. Five protein-coding genes (COII, ATP 6, COIII, ND3 and ND4) ended with incomplete stop codon T. The 22 tRNA genes with the size ranging from 65 bp to 73 bp were interspersed along the whole genome. The D-loop region containing tandem repetition was 1675 bp in length and heavily biased to A + T nucleotides.

[Detection of 1,4-dioxane in water by membrane extraction-gas chromiatgraphy/differential mobility spectrometry].

The method of detecting trace 1,4-dioxane in water using membrane extraction coupled with gas chromatography/differential mobility spectrometry (GC/DMS) was developed. The parameters including radio frequency voltage, sampling flow rate, permeation time and trapping time were optimized to 1000 V, 50 mL/min, 30 min and 150 s, respectively. The linear range for dioxane was obtained from 2.0 µg/L to 20.0 µg/L. The LOD was found to be 0. 67 µg/L. The specificity towards 1,4-dioxane in the presence of five chlorinated hydrocarbons was improved by using two-dimensional GC separation with optimized DMS compensation voltage. This method paves a way for developing field-deployable sensors for real-time monitoring contaminants in groundwater.

Detection of nitrobenzene compounds in surface water by ion mobility spectrometry coupled with molecularly imprinted polymers.

Ion mobility spectrometry (IMS) was explored in the selective detection of nitrobenzene compounds in industrial waste water and surface water, and the selectivity was theoretically elucidated with the transformation energy in the product ion formation reaction. A linear detection range of 0.5-50 ppm and a limit of detection (LOD) of 0.1 ppm were found for 2,4,6-trinitrotoluene (TNT). With the IMS as the detection system of molecularly imprinted polymer (MIP) separation technique, the MIP-IMS system was proved to be excellent method to detect trace amount of nitrobenzene compounds in surface water, in which more than 87% of nitrobenzene compounds could be adsorbed on MIPs with 90-105% of recovery.

Sensitive detection of black powder by stand-alone ion mobility spectrometer with chlorinated hydrocarbon modifiers in drift gas.

This paper introduces a simple method for selective and sensitive detection of black powder by adding chlorinated hydrocarbons in the drift gas instead of changing the structure of conventional ion mobility spectrometer (IMS). The function of chloride modifiers was to substitute Cl(-)(H2O)n for [O2⁻ (H2O)(n)] in the drift region so as to avoid the overlap between O2⁻ (H2O)(n) and sulfur ion peaks. Among CH2Cl2, CHCl3 and CCl4, CCl4 was chosen as the modifier due to the best peak-to-peak resolution and stability towards the fluctuation of modifier concentration. With 1.4 ppm CCl4 as the modifier, the minimum detectable quantity of 0.1 ng for sulfur was achieved. Moreover, this method showed the ability for detection of common explosives at sub-nanogram level, such as black powder (BP), ammonium nitrate fuel oil (ANFO), 2,4,6-trinitrotoluene (TNT), and pentaerythritol tetranitrate (PETN). In summary, this method requiring no configuration modification has high sensitivity and selectivity, and consumes trace amount of modifier. And these characteristics make it easy to be adopted in current deployed IMS to detect black powder explosives.

[Nano-electrospray ionization-ion mobility spectrometry and its combination with high performance liquid chromatography].

A nano-electrospray ionization-ion mobility spectrometer (nanoESI-IMS) was built up. Firstly, the effects of the parameters such as drift gas flow rate and solvent flow rate on the desolvation capability were studied and optimized. Then, a series of compounds were used to characterize the nanoESI-IMS system. The results showed that, complete desolvation was achieved for nano-electrospray ion droplets with the nanoESI-IMS apparatus. The limit of detection of this instrument for trioctylamine could reach 10 microg/L. Finally, this instrument was coupled to the high performance liquid chromatography (HPLC) as a detector for amines analysis. A test mixture containing triethylamine, diethylamine and butylamine was successfully separated and determined by the HPLC-nanoESI-IMS system. Linear response ranges of about two orders of magnitude were achieved for triethylamine, diethylamine and butylamine with this system.

Sensitive detection of black powder by a stand-alone ion mobility spectrometer with an embedded titration region.

Sensitive detection of black powder (BP) by stand-alone ion mobility spectrometry (IMS) is full of challenges. In conventional air-based IMS, overlap between the reactant ion O2(-)(H2O)n peak and the sulfur ion peak occurs severely; and common doping methods, providing alternative reactant ion Cl(-)(H2O)n, would hinder the formation of ionic sulfur allotropes. In this work, an ion mobility spectrometer embedded with a titration region (TR-IMS) downstream from the ionization region was developed for selective and sensitive detection of sulfur in BP with CH2Cl2 as the titration reagent. Sulfur ions were produced via reactions between sulfur molecules and O2(-)(H2O)n ions in the ionization region, and the remaining O2(-)(H2O)n ions that entered the titration region were converted to Cl(-)(H2O)n ions, which avoided the peak overlap as well as the negative effect of CH2Cl2 on sulfur ions. The limit of detection for sulfur was measured to be 5 pg. Furthermore, it was demonstrated that this TR-IMS was qualified for detecting less than 5 ng of BP and other nitro-organic explosives.

Complete mitochondrial genome of Paramegophrys oshanensis (Amphibia, Anura, Megophryidae).

The complete mitochondrial genome of a stream-dwelling frog species Paramegophrys oshanensis was determined. This mitogenome was 17,747 bp in length, containing 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and a control region (D-loop). The base composition of the light strand was 28.77% A, 29.85% T, 26.26% C, and 15.11% G. Compared with most other vertebrates, this mitogenome has some different features: a non-tandem duplication of tRNA-Met gene (forming tRNA-Met1 and tRNA-Met2 genes), the replacement of tRNA-Trp gene by a 72-bp noncoding region translocated from the cluster of WANCY to the back of Cytb gene, the translocation of tRNA-Val gene from the front of 16S rRNA to the back of tRNA-Met1 gene, and the translocation of tRNA-Pro gene from the front of D-loop region to the front of tRNA-Met2 gene. Three kinds of tandem repeats with size ranging from 71 to 92 bp were detected within D-loop region.