The reciprocal exchange of goods and services among social partners is a conundrum in evolutionary biology because of its proneness to cheating, but also the behavioral and cognitive mechanisms involved in such mutual cooperation are hotly debated. Extreme viewpoints range from the assumption that, at the proximate level, observed cases of "direct reciprocity" can be merely explained by basic i...

A new public health problem arises from animal trypanosomes that afflict human by a disease called atypical human trypanosomiasis. Although humans have an innate protection against most Trypanosoma species, nineteen cases of atypical human trypanosomiasis caused by the animal trypanosome as T. b. brucei, T. vivax, T. congolense, T. evansi and T. lewisi have been recorded. Some of theserecorded ...

The black rat, Rattus rattus, consists of five karyotypic forms-2n = 42 (high C-banding); 2n = 42 (low C-banding); 2n = 40; 2n = 38; 2n = 42 Mauritius. Here, we use isozyme electrophoresis and microcomplement fixation to elucidate the genetic distance and phylogenetic relationship among each of the various karyotypic forms of R. rattus and R. norvegicus . The results show that (1) the 2n = 42 M...

Infant Syrian golden hamsters (Mesocricetus auratus) do not exhibit endogenous heat production before 3 weeks of age and do not huddle effectively during cold exposure, gaining little thermoregulatory benefit from the presence of multiple littermates. In contrast, infant Norway rats (Rattus norvegicus) produce heat endogenously and are effective at maintaining elevated body temperatures by hudd...

Eight hundred and thirteen European rodents and shrews encompassing seven different species were screened for alphacoronaviruses using PCR detection. Novel alphacoronaviruses were detected in the species Rattus norvegicus, Microtus agrestis, Sorex araneus and Myodes glareolus. These, together with the recently described Lucheng virus found in China, form a distinct rodent/shrew-specific clade w...

Hemorrhagic fever with renal syndrome (HFRS) is a zoonotic disease, which threatens public health and its incidence has increased sharply up to the present time in southern China. A survey of HFRS including in both the natural hosts and humans conducted in Qingyuan, southern China, during 2011-2013 revealed that one, two and seven confirmed cases of HFRS occurred in 2011, 2012 and 2013, respect...

The geotropic orientation of Rattus rattus (roof rat) obeys the equations previously found applicable for Rattus norvegicus. The former is more sensitive, geotiopically, and the numerical values of the constants in the equations for the two forms are found to differ significantly. Certain consequences of this difference are pointed out.

An investigation of helminths in the Norway (brown) rat, Rattus norvegicus, and roof rat, Rattus rattus, from Chiang Mai Moat during May to August 1995, was done. Thirty-three out of thirty-eight trapped rats were infected (86.84%); 16 R. norvegicus (100%) and 17/22 R. rattus (77.27%). The rat was infected with 10 helminth species: 4 trematodes, Centrocestus sp (2.63%), Echinostoma ilocanum (10...

Rats are capable to harbor various pathogens, among which certain species of zoonotic parasites are included. A long-term detection of parasite fauna of rats has sporadically been carried out in Iran. Abundance of these vertebrate pests is of great importance as regards public health issue. The present paper is focused on a digenean trematode Plagiorchis muris, obtained during a comprehensive s...

If acquired associations are to accurately represent real relevance relations, there is motivation for the hypothesis that learning will, in some circumstances, be more appropriately modelled, not as direct dependence, but as conditional independence. In a serial compound conditioning experiment, two groups of rats were presented with a conditioned stimulus (CS1) that imperfectly (50%) predicte...