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

Neural Activation During Tonic Pain and Interaction Between Pain and Emotion in Bipolar Disorder: An fMRI Study

Objective: Pain and affective disorders have clear clinical relevance; however, very few studies have investigated the association between pain and bipolar disorder. This study investigated the brain activity of patients with bipolar disorder (BPs) undergoing tonic pain and assessed the interaction between pain and emotion.Methods: Ten BPs and ten healthy controls (HCs) were exposed to emotional pictures (positive, neutral, or negative), tonic pain only (pain session), and emotional pictures along with tonic pain (combined session). A moderate tonic pain was induced by the infusion of hypertonic saline (5% NaCl) into the right masseter muscle with a computer-controlled system. Whole-brain blood oxygenation level dependent (BOLD) signals were acquired using 3T functional resonance imaging (fMRI).Results: Ten BPs and ten healthy participants were included in the final analysis. During the pain session, BPs accepted more saline, but showed lower pain rating scores than HCs. When experiencing pain, BPs showed a significant decrease in the BOLD signal in the bilateral insula, left inferior frontal gyrus (IFG), and left cerebellum as compared with HCs. In the combined session, the activated regions for positive mood (pain with positive mood > baseline) in BPs were the left cerebellum, right temporal gyrus, and left occipital gyrus; the activated regions for negative mood (pain with negative mood > baseline) were the right occipital gyrus, left insula, left IFG, and bilateral precentral gyrus.Conclusions: This study presents the preliminary finding of the interaction between pain and emotion in BPs. BPs exhibited lower sensitivity to pain, and the activation of insula and IFG may reflect the interaction between emotion and pain stimulus

SECOND PAIN PROCESSING TRACED BY ELECTRO- AND MAGNETO- ENCEPHALOGRAPHY IN HUMANS

　　　It is known that there are two kinds of pain sensation, a sharp or pricking pain associated with rapidly conducting Aδ-fibers (first pain), and a dull or burning pain associated with slowly conducting C-fibers (second pain). We activated C-fibers selectively by stimulating a tiny area of the skin with a CO2 laser beam using a thin aluminum plate with numerous tiny holes as a spatial filter. Using this new method, we successfully recorded C-fiber discharges with a microneurographic study and cortical responses evoked by C-fiber stimulation using electroencephalography (EEG) and magnetoencephalography (MEG) in humans.　　　First, we investigated C-fiber discharges and cerebral potentials evoked by weak CO2 laser beams applied to a tiny skin area in five healthy subjects. Microneurography was recorded from the peroneal nerve in the right popliteal area. Cerebral potentials were recorded from the Cz electrode (vertex, based on the international 10-20 system) referred to linked earlobes. The mean conduction velocity (CV) of the five stable single units was 1.1±0.3 m/s. The mean latency of the positive peak of the cerebral potentials was 1327.4±46.2 ms, which was markedly longer than that from Aδ-fiber stimulation. In contrast, this stimulation method did not activate the Aδ- units at all. These findings indicate that this new stimulation method selectively activates C-fiber nociceptors of the skin (Chapter 5 and Qiu et al., 2003).　　　Second, we measured the CV of C-fibers in the spinothalamic tract (STT) using this method. We delivered CO2 laser pulses to tiny areas of the skin overlying the vertebral spinous processes at different levels from the 7th cervical (C7) to the 12th thoracic (T12), and recorded the cerebral evoked potentials in 11 healthy men. The mean CV of C-fibers in the STT was 2.2±0.6 m/s, which was significantly slower than that of the Aδ-fibers (10.0±4.5 m/s). This technique is novel and simple, and should be useful as a diagnostic tool for assessing the level of spinal cord lesions (Chapter 6 and Qiu et al., 2001).　　　Third, we evaluated the effects of attention, distraction and sleep on CO2 laser-evoked potentials (LEP) related to C-fibers (ultra-late LEP), since the degree of perceived pain sensations is known to be influenced by the subjects’ attention levels. CO2 laser pulses were delivered to a tiny skin area of the dorsum of the right hand. Ultra-late LEP were recorded from 10 normal subjects in 5 different conditions: control (wakefulness), attention, distraction, drowsiness and sleep (stage 2). The amplitude of ultra-late LEP was slightly increased during attention and significantly decreased during distraction, relative to the control. The ultra-late LEP greatly decreased in amplitude or almost disappeared during sleep. We confirmed that the brain responses related to signals ascending through C-fibers were greatly affected by the level of consciousness, being consistent with the findings of late LEP related to Aδ-fibers. This is the first study indicating the important characteristics of ultra-late LEP related to consciousness, suggesting that they include cognitive function and reporting that one has to be aware of changes in alertness when recording (Chapter 7 and Qiu et al., 2002).　　　Fourth, using MEG, we evaluated the cerebral regions related to second pain perception ascending through C-fibers and investigated the effect of distraction on each region. Thirteen normal subjects participated in this study. CO2 laser pulses were delivered to the dorsum of the left hand to selectively activate C-fibers. The MEG responses were analyzed using a multi-dipole model. Results showed that (1) the primary somatosensory cortex (SI), and (2) the secondary somatosensory cortex (SII) - insula were the main generators for the primary component, 1M, the mean peak latency of which was 744 ms. In addition to (1) and (2), (3) the cingulate cortex and (4) the medial temporal area (MT) were also activated for the subsequent component, 2M, the mean peak latency of which was 947 ms. During a mental calculation task (distraction), all six sources were significantly reduced in amplitude, but the SII-insula (P<0.01) and cingulate cortex (P<0.001) were more sensitive than the SI (P<0.05) and MT (P<0.05). We confirmed that the SI in the contralateral hemisphere and the SII-insula, cingulate cortex and MT in the bilateral hemispheres play a major role in second pain perception, and all sites were greatly affected by changes in the attention levels, indicating that these regions are related to the cognitive aspect of second pain perception, and particularly to activities in the cingulate cortex (Chapter 8 and Qiu et al., 2004)

High-Throughput Identification of Antimicrobial Peptides from Amphibious Mudskippers

Widespread existence of antimicrobial peptides (AMPs) has been reported in various animals with comprehensive biological activities, which is consistent with the important roles of AMPs as the first line of host defense system. However, no big-data-based analysis on AMPs from any fish species is available. In this study, we identified 507 AMP transcripts on the basis of our previously reported genomes and transcriptomes of two representative amphibious mudskippers, Boleophthalmus pectinirostris (BP) and Periophthalmus magnuspinnatus (PM). The former is predominantly aquatic with less time out of water, while the latter is primarily terrestrial with extended periods of time on land. Within these identified AMPs, 449 sequences are novel; 15 were reported in BP previously; 48 are identically overlapped between BP and PM; 94 were validated by mass spectrometry. Moreover, most AMPs presented differential tissue transcription patterns in the two mudskippers. Interestingly, we discovered two AMPs, hemoglobin β1 and amylin, with high inhibitions on Micrococcus luteus. In conclusion, our high-throughput screening strategy based on genomic and transcriptomic data opens an efficient pathway to discover new antimicrobial peptides for ongoing development of marine drugs

Changes of gamma-band oscillatory activity to tonic muscle pain

It is well know that phasic pain could induce suppression of alpha oscillations and enhancement of gamma oscillations. However, the cortical responses to tonic pain, especially tonic pain originating from deep tissue, which was proposed to better resemble the clinical pain, are not well understood. Here we aimed to investigate electroencephalographic (EEG) responses to tonic muscle pain. EEG signals and pain perceptions of three order-counterbalanced conditions: innocuous condition (A, infusion of isotonic saline), noxious conditions with low (B) and medium (C) intensities (infusion of hypertonic saline) were recorded from 43 subjects. We observed the enhancement of gamma oscillations in frontal-central region in condition C, as compared to either condition A or B. Positive relationship between the amplitude of gamma oscillations and pain intensity was also observed in frontal-central region. Therefore, we provide novel evidence for the encoding of frontal-central gamma oscillations in tonic pain processing. (C) 2016 Elsevier Ireland Ltd. All rights reserved.</p