Social isolation-induced aggression potentiates anxiety and depressive-like behavior in male mice subjected to unpredictable chronic mild stress

Background

Accumulating epidemiological evidence shows that life event stressors are major vulnerability factors for psychiatric diseases such as major depression. It is also well known that social isolation in male mice results in aggressive behavior. However, it is not known how social isolation-induced aggression affects anxiety and depressive-like behavior in isolated male mice subjected to unpredictable chronic mild stress (CMS), an animal model of depression.

Methodology/Principal Findings

C57/B6 male mice were divided into 3 groups; non-stressed controls, in Group I; isolated mice subjected to the CMS protocol in Group II and aggression by physical contact in socially isolated mice subjected to the CMS protocol in Group III. In the sucrose intake test, ingestion of a 1% sucrose solution by mice in Groups II and III was significantly lower than in Group I. Furthermore, intake of this solution in Group III mice was significantly lower than in Group II mice. In the open field test, mice in Group III, showed reduced locomotor activity and reduced entry and retention time in the central zone, compared to Groups I and II mice. Moreover, the distances moved in 1 hour by Group III mice did not differ between night and morning. In the light/black box test, Groups II and III animals spent significantly less time in the light box compared to Group I animals. In the tail suspension test (TST) and forced swimming test (FST), the immobility times of Group II and Group III mice were significantly longer than in Group I mice. In addition, immobility times in the FST were significantly longer in Group III than in Group II mice.

Conclusions/Significance

These findings show that social isolation-induced aggression could potentiate anxiety and depressive -like behaviors in isolated male mice subjected to CMS.     

Insecticide susceptibility and resistance of Culex tritaeniorhynchus (Diptera: Culicidae) larvae collected from Gwangju,Republic of Korea

The susceptibility of Culex tritaeniorhynchus collected from Gwangju, Jeollabuk Province, Republic of Korea (ROK) to insecticides was evaluated under laboratory conditions using ten insecticides (7 pyrethroids and 3 organophosphates) that are currently applied by local public health centers in the ROK. Based on the values of median lethal concentration (LC₅₀), Cx. tritaeniorhynchus larvae were most susceptible to chlorpyrifos (0.006 ppm), fenitrothion (0.022 ppm), fenthion (0.035 ppm) and bifenthrin (0.038 ppm), and were least susceptible to esbiol (1.722 ppm). In comparative resistance tests, the resistance ratios (RRs) of seven insecticides were compared among each other using two strains of Cx. tritaeniorhynchus that were collected from the same locality during 1992 and 2010. Culex tritaeniorhynchus demonstrated significantly increased RRs to pyrethroids over time, while demonstrating decreased RRs among the organophosphates. Among the pyrethroids, permethrin had the highest RR values of 182.1‐ and 833.3‐fold differences, followed by etofenprox with RRs of 138.4‐ and 224.1‐fold differences in values of LC₅₀ and concentration that produced 90% mortality (LC₉₀), respectively. Culex tritaeniorhynchus strains demonstrated the least amount of change in susceptibility to the organophosphates, chlorpyrifos, fenitrothion and fenthion with 0.020‐, 0.019‐ and 0.001‐fold differences in resistance ratios (RRLC₅₀), respectively.     

Black light trap collections in Wangging county and Yanji city,Jilin Province,China, August 2006–2007

Adult mosquito surveillance was conducted using black light traps in August of 2006 and 2007 at Wangging county and Yanji city, Jilin Province, China to identify the distribution of anopheline mosquitoes in northern China. A total of 2459 female mosquitoes comprising three genera and eight species including Anopheles (Anopheles) lesteri, An. (Ano.) kleini, An. (Ano.) pullus, Culex inatomii, Cx. orientalis, Cx. pipiens, Cx. bitaeniorhynchus and Aedes vexans nipponii were collected. The most commonly collected species was An. kleini which had not been previously reported from China. Anopheles sinensis sensu stricto is commonly collected throughout China, but was not collected from these areas.     

PROTASPIDES OF UPPER CAMBRIAN APHELASPIS (PTYCHOPARIIDA, TRILOBITA) AND RELATED SPECIES WITH THEIR TAXONOMIC IMPLICATIONS

Abstract:  The ontogeny of Aphelaspis brachyphasis is illustrated and described on the basis of newly discovered silicified material from the McGill section, Nevada, USA. Protaspides of three other Aphelaspis species are redescribed. Of ptychopariide species for which protaspides have been documented, the protaspides of those previously considered to be closely related to Aphelaspis are illustrated herein. Protaspides of Aphelaspis are most similar to those of Olenus , supporting previous taxonomic suggestions that the Aphelaspidinae is closely related to the Olenidae and may be assigned to the Olenacea. The protaspides of Housia share few similarities with those of Aphelaspis , contradicting the hypothesis that these genera are placed together within the Pterocephaliidae.     

A Model Approach for Studying Race: Provocative Theory, Sound Science, and Very Good History

The Problem of Race in the Twenty-First Century. Thomas C. Holt. Cambridge, MA: Harvard University Press, 2002. 146 pp.
Race in Mind: Race, IQ, and Other Racisms. Alexander Alland Jr. New York: Palgrave Macmillan, 2002. 219 pp.
The Funding of Scientific Racism: Wickliffe Draper and the Pioneer Fund. William H. Tucker. Urbana: University of Illinois Press, 2002. 286 pp.