Population Size, Genetic Diversity and Molecular Evidence of a Recent Population Bottleneck in Hynobius chinensis, an Endangered Salamander Species

Severe population declines can reduce species to small populations, offering permissive conditions for deleterious processes. For example, following such events, species can become prone to inbreeding and genetic drift which can lead to a loss of genetic diversity and evolutionary potentials. Hynobius chinensis is a poorly studied very rare and declining endangered amphibian species endemic to China in Changyang County. We investigated adult census population size by monitoring breeding populations from 2015 to 2018, developed microsatellite markers from the transcriptome and used them to investigate genetic diversity, and a population bottleneck in this species. We found H. chinensis in 4 different localities in a total area of 2.18 km2 and estimated the overall adult census population size at 386–404 individuals. The adult census size (mean ± SE) per breeding pond ranged from 44 ± 6 to 141 ± 8 individuals and appeared smaller than that reported in closely related species in undisturbed habitats. We developed and characterized 13 microsatellite markers in total. Analysis of data at 7 loci (N = 118) in Hardy-Weinberg equilibrium gathered from the largest population showed that genetic diversity level was low. The average number of alleles per locus was 2.14. The observed and expected heterozygosities averaged 0.38 and 0.40, respectively. The inbreeding coefficient was –0.06. All tests performed to investigate a population bottleneck, i.e. The Garza-Williamson test, Heterozygosity excess test, Mode shift test of allele frequency, and effective population size estimates detected a population bottleneck. The contemporary and the historical effective population sizes were estimated at 36 and 234 individuals, respectively. We argue that as bottleneck effects, the studied population may have become prone to genetic drift and inbreeding, losing microsatellite alleles and heterozygosity. Our results suggest that populations of H. chinensis may have been extirpated in the study area

Protective Effects of Hydrogen against Low-Dose Long-Term Radiation-Induced Damage to the Behavioral Performances, Hematopoietic System, Genital System, and Splenic Lymphocytes in Mice

Molecular hydrogen (H2) has been previously reported playing an important role in ameliorating damage caused by acute radiation. In this study, we investigated the effects of H2 on the alterations induced by low-dose long-term radiation (LDLTR). All the mice in hydrogen-treated or radiation-only groups received 0.1 Gy, 0.5 Gy, 1.0 Gy, and 2.0 Gy whole-body gamma radiation, respectively. After the last time of radiation exposure, all the mice were employed for the determination of the body mass (BM) observation, forced swim test (FST), the open field test (OFT), the chromosome aberration (CA), the peripheral blood cells parameters analysis, the sperm abnormality (SA), the lymphocyte transformation test (LTT), and the histopathological studies. And significant differences between the treatment group and the radiation-only groups were observed, showing that H2 could diminish the detriment induced by LDLTR and suggesting the protective efficacy of H2 in multiple systems in mice against LDLTR

Effect of B on Microstructure and Properties of Surfacing Layer of Austenitic Stainless Steel Flux Cored Wire

In order to study the effect of element B on the corrosion resistance of stainless steel-based flux cored wire surfacing alloy, a stainless steel surfacing layer was prepared on the surface of carbon steel plate by melt electrode gas shielded welding, and then the microstructure, electrochemical corrosion resistance, and wear resistance of the surfacing layer were analyzed. The results show that the surfacing layer of surfacing alloy presents M2B and Fe3(C, B) phases based on austenite. Boride formed in deposited metal has good corrosion resistance. Therefore, adding the proper amount of B can significantly improve the corrosion resistance of the surfacing layer. When the boron content is 2%, the corrosion resistance is the best. The minimum self-corrosion current density is 1.75766 × 10−11 mA·cm2, and the maximum self-corrosion potential is −0.254438 V. Maximum impedance curve radius. At this time, the wear resistance of the surfacing layer is also the best

Effect of N on corrosion resistance of Fe-Cr-Ni-Mo-Mn alloy

In order to develop the Fe-Cr-Ni-Mo-Mn-N corrosion resistant alloys, analyze the influence of nitrogen on the corrosion resistance of Fe-Cr-Ni-Mo-Mn alloy, adjust the N content in the alloy system, and Flux cored wires with different N content were prepared. They were surfaced on low carbon steel by MIG welding. The phase composition, microstructure and corrosion resistance of the cladding metal were analyzed to study the effect of N content on the structure and performance of the surfacing metal. The results show that the addition of nitrogen does not change the matrix structure (which is Fe-Ni-Cr austenite), but with the increase of nitrogen content, the precipitation of nitrides (Cr _2 (C,N) and BN)is accompanied; when the amount of nitrogen added reaches 1.0%, the corrosion resistance of the surfacing metal is the best. At this time, the self-corrosion current density is at least 1.569 × 10 ^–9 mA cm ^−2 and the self-corrosion potential is at most −0.318 V. The addition of nitrogen can promote the formation of austenite and nitride, inhibit the appearance of carbides, avoid the phenomenon of poor Cr, and improve the corrosion resistance of the material

New Evidence Suggests Southern China as a Common Source of Multiple Clusters of Highly Pathogenic H5N1 Avian Influenza Virus

Highly pathogenic H5N1 avian influenza is considered an avian disease, although there is some evidence of limited human-to-human transmission of the virus. A global effort is underway to control or eradicate the highly pathogenic H5N1 avian influenza virus in poultry and prevent human exposure, both of which may also reduce the risk of pandemic emergence. Hemagglutinin gene sequences from 215 human H5N1 influenza viruses were used to trace the source and dispersal pattern of human H5N1 influenza viruses on a global scale. A mutation network and phylogenetic analyses of the hemagglutinin gene show that human H5N1 influenza viruses can be clearly divided among 4 clusters across geographic space. On the basis of analysis of the N-glycosylation sites at positions 100 and 170 in the hemagglutinin protein, human H5N1 influenza viruses were also divided into 3 types. When we combined these analyses with geographic information system data analyses, we found that Southern China is often a common source of multiple clusters of H5N1 influenza viruses and that each cluster has different dispersal patterns and individual evolutionary features. In summary, the genetic evidence presented here provides clear evidence for multiple clusters of human H5N1 influenza viruses that initially originated in Southern China

Disrupted Regional Spontaneous Neural Activity in Mild Cognitive Impairment Patients with Depressive Symptoms: A Resting-State fMRI Study

Depressive symptoms are common in individuals with mild cognitive impairment (MCI) who have an increased risk of dementia. It is currently unclear whether the pattern of spontaneous brain activity in patients with MCI differs between subjects with and without depressive symptoms. The current study sought to investigate the features of spontaneous brain activity in MCI patients with depressive symptoms (D-MCI) using coherence regional homogeneity (CReHo) analysis with resting-state functional magnetic resonance imaging (rsfMRI). We obtained rsfMRI data in 16 MCI patients with depressive symptoms and 18 nondepressed MCI patients (nD-MCI) using a 3 T scanner. Statistical analyses were performed to determine the regions in which ReHo differed between the two groups in specific frequency bands, slow-4 (0.027–0.073 Hz) and slow-5 (0.010–0.027 Hz), and typical bands (0.01–0.08 Hz). Correlation analyses were performed between the CReHo index of these regions and clinical variables to evaluate the relationship between CReHo and pathophysiological measures in the two groups. Our results showed that D-MCI patients exhibited significantly higher CReHo in the left Heschl’s gyrus and left thalamus and lower CReHo in the left postcentral gyrus in the typical frequency band. In the slow-4 frequency band, D-MCI patients showed significantly higher CReHo in the left Heschl’s gyrus and left thalamus. In the slow-5 frequency band, D-MCI patients exhibited significantly lower CReHo in the superior medial prefrontal gyrus. In addition, the results revealed that CReHo values in the left thalamus were positively correlated with Hamilton Depression Rating Scale (HAMD) scores in D-MCI patients. These results suggest that the sensorimotor network may be one of the main pathophysiological factors in D-MCI