Diet composition of the golden jackal (Canis aureus, L.) in Bulgaria, where the largest jackal population in Europe occurs, has been studied by scat analysis in a typical and newly occupied agricultural environment. The study was carried out during late summer and early autumn, a period when small mammal density is high. The food of the jackal typically consisted of small-sized and wild-living prey species. Rodents have been found to represent the primary food of the jackal (biomass estimation: 59.3 %, mainly Microtus spp.), and the European brown hare (Lepus europaeus, 20.1 %) and plants (19.7 %, mainly fruits) are secondary foods. Other prey, such as birds (mainly passerines), reptiles and invertebrates had been consumed in a low biomass ratio. No remains of wild ungulate and domestic animals have been detected in the studied scats.
A comparative study of resting metabolic rate was conducted for the temperature range 10-37 °C for four rodent species, northern three-toed jerboa (Dipus sagitta) (body mass, Mb 79.2±6.8 g, n = 25), midday gerbil (Meriones meridianus) (Mb = 45.0±8.1 g, n = 10), desert hamster (Phodopus roborovskii) (Mb = 15.4±2.9 g, n = 26, and striped hamster (Cricetulus barabensis) (Mb = 24.8±4.0 g, n = 7) in the Ordos desert in summer (July), 1997. The minimum resting metabolic rates were 1.14±0.25 ml O2/g.h for three-toed jerboa, 1.35±0.3 ml O2/g.h for midday gerbil, 2.98±0.65 ml O2/g.h for desert hamster, and 2.75±0.37 ml O2/g.h for striped hamster. The thermal neutral zones (TNZ) were wide in the three desert species that was 26~37 °C in jerboa, 26~35 °C in gerbil, and 24~34 °C in desert hamster, respectively. For the non-desert species, striped hamster, it was 26~30 °C. The results do not confirm the hypothesis that desert rodents generally have lower metabolic levels than non-desert species. The high metabolic rates of these four rodent species were interpreted to be influenced by the stable availability of food resources and low environmental temperature in the Ordos Plateau. our results partly support the hypothesis that the metabolism characteristics are determined by food resources and environment temperature for animals living in arid regions.
The Southern birch mouse, Sicista subtilis (Pallas, 1773), is one of the rarest and least known small mammal species in Europe. At present, the occurrence of its subspecies, the S. subtilis trizona (Frivaldszky, 1865), is confined to Hungary. The last living individual of this rare subspecies was caught in 1926. Prior to 2006, individuals were detected only from owl-pellets, but at fewer and fewer localities. After an 80 year hiatus in the records, the first living specimen was trapped on 21st June, 2006 in the Borsodi Mezőség (NE Hungary), at a location well known from previous skeletal records. In the same year, another 42 specimens were trapped. Recapture occurred only three times. The last three specimens were captured on 22nd September in 2006. So far S. subtilis trizona has occurred mainly in weed vegetation Carduetum acanthoidis and in its edge. These patches mostly border on abandoned plough-land vegetation (Convolvulo–Agropyretum repentis) dominated by annual grasses. The majority of the habitat had been ploughed a short time earlier (approx. 10–15 years), and barns and other farm-buildings occupying smaller part of it.
In humans, CD46 has been detected on the acrosomal membrane in sperm, in contrast to widespread surface expression on somatic cells where it plays a key role in the protection from complement attack. In rodents, CD46 is expressed solely on the acrosomal membrane of mature sperm and their immediate precursors, spermatids. A monoclonal antibody against the short consensus repeat (SCR1) ectodomain of CD46 blocks binding of human sperm to zona-free oocytes in vitro. However, CD46-knockout mice are fertile and have an accelerated spontaneous acrosome reaction. Wild-caught field mice (Apodemus) also exhibit a rapid acrosome reaction and CD46 is not expressed in Apodemus sperm. CD46 may, therefore, play a role in stabilization of the acrosomal membrane. Two other complement regulatory proteins, CD55 and CD59, are localized on the plasma membrane of mammalian sperm. In human sperm, CD55 and CD59 are expressed also on the inner acrosomal membrane. It remains to be clarified what is the role of CD46, CD55 and CD59 during fertilization and what are the advantages of not expressing CD46 in field mice sperm.