Amphetamine-induced aggression is enhanced in rats pre-treated with the anabolic androgenic steroid nandrolone decanoate

Aggression is one of the most commonly reported psychiatric side effects among anabolic-androgenic steroids (AAS) users. Furthermore, anecdotal stories say the aggression is even more profound when a current, or former, AAS-user consumes other drugs of abuse such as amphetamine and alcohol. In the present study, we examined the effect of amphetamine on defensive reactivity and defensive aggression in Sprague-Dawley rats after chronic AAS treatment (daily intramuscular [i.m.] injections with 15 mg/kg nandrolone decanoate [ND] for 14 days). Defensive reactions in rodents occur in response to a real threat, but also to perceived provocation, for example, elicited by innocuous stimuli as reaction towards the experimenter. The defensive reactivity and aggression test employed in this study evaluates each rat's reaction towards four different stimuli (I: approach of a rod; II: startle to an air puff; III: poking with a rod at the flanks, and IV: capturing with a gloved hand) at two different occasions. Immediately following the ND treatment period, no change in the defensive response was found. Nevertheless, an amphetamine challenge given 3 weeks after the last ND or vehicle injection induced a marked increased defensive aggressive response in the ND, compared to vehicle-pre-treated rats. Both ND- and vehicle-pre-treated rats receiving amphetamine were found to be more aggressive than comparable groups receiving a saline injection. It can be concluded that pre-treatment with ND modulates the behavioral response to amphetamine and induces long lasting changes in the behavioral response.     

A critical step in the folding of influenza virus HA determined with a novel folding assay

Most principles of protein folding emerged from refolding studies in vitro on small, soluble proteins, because large ones tend to misfold and aggregate. We developed a folding assay allowing the study of large proteins in detergent such that the extent of cellular assistance required for proper folding can be determined. We identified a critical step in the in vivo folding pathway of influenza virus hemagglutinin (HA). Only the formation of the first few disulfides in the top domain of HA required the intact endoplasmic reticulum. After that, HA proceeded to fold efficiently in a very dilute solution, despite its size and complexity. This study paves the way for detailed structural analyses during the folding of complex proteins.     

Areas of endemism: an improved optimality criterion

The grid-based method to identify areas of endemism proposed by Szumik et al. is extended. The improvements include the ability to assign scores of endemicity to sets of disjoint areas, and to have each species contribute more to the score of endemicity of an area, or less, according to how well its distribution matches the area. The modified method also allows for partially overlapping areas; an area partially overlapping with another one of higher score is retained when the set of lower score has a minimum proportion of species endemic to it. Algorithms to evaluate areas of endemism under this criterion are discussed, and implemented in a computer program (NDM). The new algorithms allow evaluation of much larger data sets.     

Akt2 negatively regulates assembly of the POSH-MLK-JNK signaling complex

We demonstrate that POSH, a scaffold for the JNK signaling pathway, binds to Akt2. A POSH mutant that is unable to bind Akt2 (POSH W489A) exhibits enhanced-binding to MLK3, and this increase in binding is accompanied by increased activation of the JNK signaling pathway. In addition, we show that the association of MLK3 with POSH is increased upon inhibition of the endogenous phosphatidylinositol 3-kinase/Akt signaling pathway. Thus, the assembly of an active JNK signaling complex by POSH is negatively regulated by Akt2. Further, the level of Akt-phosphorylated MLK3 is reduced in cells expressing the Akt2 binding domain of POSH, which acts as a dominant interfering protein. Taken together, our results support a model in which Akt2 binds to a POSH-MLK-MKK-JNK complex and phosphorylates MLK3; phosphorylation of MLK3 by Akt2 results in the disassembly of the JNK complex bound to POSH and down-regulation of the JNK signaling pathway.     

Every rose has its thorn: Infants' responses to pointed shapes in naturalistic contexts

Plants produce dangerous chemical and physical defenses that have shaped the physiology and behavior of the herbivorous predators that feed on them. Here we explore the impact that these plant defenses may have had on humans by testing infants' responses to plants with and without sharp-looking thorns. To do this, we presented 8- to 18-month-olds with plants and control stimuli and measured their initial reaching behavior and subsequent object exploration behavior. Half of the stimuli had sharp-looking thorns or pointed parts while the other half did not. We found that infants exhibited both an initial reluctance to touch and minimized subsequent physical contact with plants compared to other object types. Further, infants treated all plants as potentially dangerous, whether or not they possessed sharp-looking thorns. These results reveal novel dimensions of a behavioral avoidance strategy in infancy that would mitigate potential harm from plants.