The looming stimulus-evoked flight response to approaching predators is a defensive behavior in most animals. However, how looming stimuli are detected in the retina and transmitted to the brain remains unclear. Here, we report that a group of GABAergic retinal ganglion cells (RGCs) projecting to the superior colliculus (SC) transmit looming signals from the retina to the brain, mediating the looming-evoked flight behavior by releasing GABA. GAD2-Cre and vGAT-Cre transgenic mice were used in combination with Cre-activated anterograde or retrograde tracer viruses to map the inputs to specific GABAergic RGC circuits. Optogenetic technology was used to assess the function of SC-projecting GABAergic RGCs (scpgRGCs) in the SC. FDIO-DTA (Flp-dependent Double-Floxed Inverted Open reading frame-Diphtheria toxin) combined with the FLP (Florfenicol, Lincomycin & Prednisolone) approach was used to ablate or silence scpgRGCs. In the mouse retina, GABAergic RGCs project to different brain areas, including the SC. ScpgRGCs are monosynaptically connected to parvalbumin-positive SC neurons known to be required for the looming-evoked flight response. Optogenetic activation of scpgRGCs triggers GABA-mediated inhibition in SC neurons. Ablation or silencing of scpgRGCs compromises looming-evoked flight responses without affecting image-forming functions. Our study reveals that scpgRGCs control the looming-evoked flight response by regulating SC neurons via GABA, providing novel insight into the regulation of innate defensive behaviors.
Animals ; Superior Colliculi/physiology* ; Retinal Ganglion Cells/physiology* ; GABAergic Neurons/physiology* ; Mice, Transgenic ; Mice ; Optogenetics ; Visual Pathways/physiology* ; Mice, Inbred C57BL ; Photic Stimulation/methods* ; gamma-Aminobutyric Acid/metabolism* ; Male

Objective:To study the multi-locus sequence typing (MLST) gene characteristics of Brucella isolates in Guizhou Province. Methods:Brucella strains, which were isolated from 2017 to 2021 in Guizhou Province (preserved in the Bacterial and Viral Seed Bank of Guizhou Center for Disease Control and Prevention) were identified Brucella and species/types by BCSP31-PCR and AMOS-PCR methods, respectively. MLST method was used for genotyping, and Biometrics 8.0 software was used for cluster analysis of the typing results. Results:A total of 32 strains of Brucella were isolated in Guizhou Province and identified as Brucella melitensis ( B.melitensis) by BCSP31-PCR and AMOS-PCR methods. These strains were classified into 2 ST types (ST8 and ST39) by MLST method, with 28 strains of ST8 type(87.5%) and 4 strains of ST39 type (12.5%). The 28 strains of ST8 type were distributed in 7 cities (prefectures) of Guizhou Province, while the 4 strains of ST39 type were only found in Qianxinan Buyi and Miao Autonomous Prefecture. The cluster analysis results showed that ST8 and ST39 types strains were clustered in a group with the reference strain of B.melitensis, and there was only one nucleotide site difference between ST39 and ST8 types in the glk gene, indicating a close genetic relationship. Conclusions:B.melitensis is the main pathogen of the brucellosis epidemic in Guizhou Province in recent years. ST8 is the dominant MLST genotype in Guizhou Province.

Objective To explore the changes of plasma melatonin(MT)level in hypoxic-ischemic encephalopathy(HIE)neonates,and elucidate the function of rnelatonin in the pathogenesis and the prognosis of HIE.Methods Fourty HIE neonates were divided into 2 groups,20 mild HIE neonates and 20 moderate or severe HIE ones.The femoral vein blood were collected in 48 h and on 7 d after birth in mild HIE group,and in 48 h,on 7 d and(14±4)d after birth in moderate on severe HIE group.Twenty normal term infants served as control group.The level of plasma MT was determined with enzyme-labeled immunosorbent assay.Results Compared with control group[(8.003±1.840)ng/L],The MT level in mild HIE group in 48 h after birth[(13.311±4.025)ng/L]was higher(P＜0.01),but there was no difference on 7 d[(6.605±1.269)ng/L](P＞0.05);The MT level in moderate or severe HIE group in 48 h after birth[(5.487±1.997)ng/L]was lower(P＜0.01),but it was higher on 7 d[(16.201±5.594)ng/L](P＜0.01),there was no difference on(14±4)d[(6.799±1.765)ng/L](P＞0.05).Conclusion MT may have protective action on HIE.The prognosis of HIE with rising MT level in 48 h after birth is better than that with lower MT level.