Ants medicate to fight disease

Parasites are ubiquitous, and the ability to defend against these is of paramount importance. One way to fight diseases is self‐medication, which occurs when an organism consumes biologically active compounds to clear, inhibit, or alleviate disease symptoms. Here, we show for the first time that ants selectively consume harmful substances (reactive oxygen species, ROS) upon exposure to a fungal pathogen, yet avoid these in the absence of infection. This increased intake of ROS, while harmful to healthy ants, leads to higher survival of exposed ants. The fact that ingestion of this substance carries a fitness cost in the absence of pathogens rules out compensatory diet choice as the mechanism, and provides evidence that social insects medicate themselves against fungal infection, using a substance that carries a fitness cost to uninfected individuals.     

Unraveling the Relationship between Trait Negative Affectivity and Habitual Symptom Reporting

Objective

In two studies, we aimed at further elucidating the relationship between trait negative affectivity (NA) and habitual symptom reporting (HSR) by relating these variables to measures of executive function, trait questionnaires, and effects of emotion induction.

Methods

Healthy female participants (N = 75) were selected on their scores for trait NA and for the Checklist for Symptoms in Daily Life. Three groups were compared: (1) low NA-low HSR; (2) high NA-low HSR; and (3) high NA-high HSR (low NA-high HSR did not occur). In study 1, participants underwent a Parametric Go/No-go Task and a Stroop Color-Word test, and trait questionnaires measured alexithymia and absorption. Forty-five participants (N = 15 in each group) were further engaged in study 2 to induce state NA using an affective picture paradigm.

Results

Impaired inhibition on the Stroop and Go/No go Task characterized high trait NA, but not high HSR, whereas alexithymia and absorption were elevated in HSR, regardless of trait NA. Negative picture viewing induced elevated state NA in all groups, but only high HSR also reported more bodily symptoms. This effect was moderated, but not mediated by state NA.

Conclusion

High trait NA is a vulnerability factor but not a sufficient condition to develop HSR. Deficient inhibition is related to the broad trait of NA, whereas the moderating effect of state NA on symptom reporting is specific for high HSR. Understanding processes related to alexithymia and absorption may specifically help to explain elevated HSR.     

Worker reproduction in Formica ants

A potential tragedy of the commons arises in social-insect colonies where workers are fertile if egg-laying workers decrease their contribution to other tasks. We studied worker ovary development and egg laying in relation to kin structure, colony size, and the presence of a queen in nine species (11 populations) of Formica ants. Workers were highly fertile and laid eggs in the presence of a queen in five out of the seven species where egg samples were obtained. Worker fertility correlated neither with colony size nor with kin structure, which suggests that colony-level costs and efficiency of policing precede relatedness as the most important conflict determinant. We conclude that careful quantification of the costs of worker reproduction and policing is essential for inferences about the tragedy of the commons.     

T cells that are naturally tolerant to cartilage-derived type II collagen are involved in the development of collagen-induced arthritis

The immunodominant T-cell epitope that is involved in collagen-induced arthritis (CIA) is the glycosylated type II collagen (CII) peptide 256-270. In CII transgenic mice, which express the immunodominant CII 256-270 epitope in cartilage, the CII-specific T cells are characterized by a partially tolerant state with low proliferative activity in vitro, but with maintained effector functions, such as IFN-γ secretion and ability to provide B cell help. These mice were still susceptible to CIA. The response was mainly directed to the glycosylated form of the CII 256-270 peptide, rather than to the nonglycosylated peptide. Tolerance induction was rapid; transferred T cells encountered CII within a few days. CII immunization several weeks after thymectomy of the mice did not change their susceptibility to arthritis or the induction of partial T-cell tolerance, excluding a role for recent thymic emigrants. Thus, partially tolerant CII autoreactive T cells are maintained and are crucial for the development of CIA.     

Early intervention with liraglutide improves glucose tolerance without affecting islet microcirculation in young Goto-Kakizaki rats

Liraglutide, an analog of glucagon-like peptide-1 (GLP-1), is an effective anti-diabetic agent with few side effects. Since native GLP-1 exerts vascular effects, we investigated changes in pancreatic islet blood flow using a non-radioactive microsphere technique, as well as insulin concentration and glucose tolerance after 17 day treatment with liraglutide in 6-week-old Goto-Kakizaki (GK) rats. Compared to saline-treated control GK rats, liraglutide limited body weight gain, decreased glycemia, improved glucose tolerance and lowered serum insulin concentration. Neither pancreatic or islet blood flow, nor pancreatic insulin content, was affected by liraglutide treatment. We conclude that early intervention with liraglutide decreases glycemia and improves glucose tolerance, thus halting the natural progression towards diabetes, without affecting islet microcirculation or pancreatic insulin content in young female GK rats.     

Purinoxydierende Fermente aus Schimmelpilzen

Zusammenfassung In einer Reihe von Schimmelpilzen — und damit (von Bakterien abgesehen) erstmals eindeutig in pflanzlichen Organismen — wurde neben Uricase auch eine Xanthindehydrase nachgewiesen. Nach den vorliegenden orientierenden Versuchen scheint sie allerdings weniger verbreitet, weniger aktiv und labiler zu sein als die Uricase.Eigenschaften, Hemmbarkeit und Kinetik des Ferments wurden näher untersucht. Die Mycelextrakte besitzen auch das Vermögen zur Oxydation von Adenin (washrscheinlich nach vorausgegangener hydrolytischer Desaminierung) und von Aldehyden; anscheinend kehrt die Doppelspezifität des tierischen Ferments beim Pilzferment wieder, was allerdings noch exakt zu beseisen wäre. Auch im Verhalten gegenüber Inhibitoren und Farbstoffacceptoren sowie in der aeroben Hydroperoxydbildung ähnelt die pflanzliche Xanthindehydrase der tierischen (Schardinger-Enzym); vermutlich ist sie ebenfalls ein Flavinferment.Jetzt: National Research Council of Egypt, Cairo.     

Vergleichende Pollenuntersuchungen an verschiedenen Lärchenrassen

Ohne Zusammenfassung     

Eiweißwürfel inSolanum demissum

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