Transgenic rabbits provide a useful biological model for the study of the regulation of mammalian genes. However, transgene integration efficiency has generally been low. Here we present a first attempt to increase the integration rate of exogenous DNA into the rabbit genome, using a double pronuclei microinjection method. Pronuclear stage rabbit embryos were recovered from superovulated NZW females, 19-20 h after hCG injection. About 5 microg/mL of exogenous DNA solution was microinjected either into one pronucleus (single microinjection, SM) or into both pronuclei (double microinjected, DM). The transgene consisted of a 2.5 kb murine whey acidic protein promoter (mWAP), 7.2 kb cDNA of the human clotting factor VIII (hFVIII), and 4.6 kb that of 3' flanking sequences of the mWAP gene. The in vitro survival of DM embryos to the blastocyst stage was lower than that of SM embryos (68 vs. 89%). Similar results were obtained using EGFP as a control gene construct. However, there was no difference in the percentage of embryos that developed into live offspring using DM (25%) vs. SM (26%). The integration frequency of mWAP-hFVIII into the genome of transgenic rabbits was 3.3% (1/30) upon SM and 8.1% (4/49) at DM (p < 0.05). All founders transmitted the transgene to their offspring in a Mendelian fashion. The SM founder female secreted 87.4 microg/mL rhFVIII in milk, with an activity of 0.594 IU/mL. The DM founder female produced 118 microg/mL rhFVIII, with activity values of 18 IU/ mL. This is the first report of transgenic rabbit production using a double microinjection technique. Our preliminary results suggest that this method can increase the efficiency of production of transgenic rabbit founders, giving a higher integration rate than single microinjection.

This study was conducted to investigate the effect of heat stress (i.e., elevated ambient temperature -Ta; 36 °C ± 3 °C) on growth performance, mortality rate, and on some haematological and biochemical parameters in different categories of gender and age of New Zealand White (NZW) rabbits. Animals were divided into two main groups (control and treatment), in each group there were 56 rabbits: adult females (n = 20), adult males (n = 4), growing females (n = 16), and growing males (n = 16). Results revealed that total and daily feed intake, feed conversion ratio, and total and daily gain in body weight for growing NZW rabbits were affected negatively by elevated Ta. Decreases in feed intake led to less protein biosyntheses and less fat deposition, which led to lower body weight gain. These observations were made in growing and adult rabbits of both genders. Analysis showed that red blood cell (RBC) counts showed alterations. Packed cell volume (PCV) (in adult females and males), white blood cell (WBC) counts (in growing females), lymphocytes (in growing males), monocytes (in growing females and adult males), basophils (in growing females and growing and adult males) were significantly (P < 0.05) decreased, and total proteins (TP) (in adult females), glucose (Glu) (in adult females), and calcium (Ca 2+ ) (in growing males and females) were significantly (P < 0.01) lower in the experimental group. Furthermore, elevated Ta increased the mortality rate (MR) in both age groups. The mortality rate was 30.36% for growing and adult rabbits of the experimental group, compared with 7.14% for the control group, and was 25% for adult compared with 34.38% for growing experimental rabbits. Exposure of NZW rabbits of both ages and genders to elevated ambient temperature (36°C ± 3 °C), negatively affected their internal homeostasis which was reflected in their growth rate and various physiological signs.

The effect of <I>Enterococcus faecium</I> CCM7420, bacteriocin-producing strain with probiotic properties and its partially purified bacteriocin PPB CCM7420 on growth performance, microflora, <I>Eimeria</I> sp. oocysts, biochemical blood parameters and glutathione-peroxidase activity in rabbits was determined. An increase in the body weight of rabbits (<I>P</I> < 0.01) was achieved after <I>E. faecium</I> CCM7420 application. A non-significant reduction of faecal <I>E. coli</I> (including haemolytic <I>E. coli</I>), coagulase-positive staphylococci (CPS) and <I>Staphylococcus aureus</I> was found in rabbits administered the <I>E. faecium</I> CCM7420 strain and lower (non-significant) counts of <I>S. aureus</I> and <I>Clostridium</I>-like sp. were detected in PPB CCM7420 group, compared to the control. In the caecum, a significant reduction of CPS was noted in both experimental groups (<I>P</I> < 0.001 and <I>P</I> < 0.05 for EG1 and EG2, respectively). Biochemical blood parameters increased in both experimental groups (<I>P</I> < 0.05 and <I>P</I> < 0.001 for EG2 and EG1, respectively). In the CCM7420 group, the lowest activity of glutathione-peroxidase was measured (<I>P</I> < 0.001). After the application of PPB CCM7420 (<I>P</I> < 0.05; day 21), a reduction of <I>Eimeria </I>sp. oocysts was recorded.

The content of cadmium and lead, as risk factors of environment, in liver and kidneys of wild animals as brown hare (Lepus europaeus), yellow-necked mouse (Apodemus flavicollis), wood mouse (Cleithrionomys glareolus), and red deer (Cervus elaphus) were studied. Samples were analyzed by the atomic absorption spectrophotometry method (AAS). The highest levels of cadmium were found in kidneys (0.213-2.387 mg/kg) of all animal species. The concentration of cadmium in liver was 0.032-0.258 mg/kg. The analysis of lead showed that the concentration of this element was higher in kidneys of yellow-necked mouse and wood mouse (0.503-0.780 mg/kg) than in liver (0.177-0.268 mg/kg). In brown hare and red deer a higher accumulation of lead in liver (0.221-1.904 mg/kg) in comparison with kidneys (0.115-0.561 mg/kg) is reported.

Two self-associating biopolymers, namely chitosan (Ch) and a high-molar-mass hyaluronan (HA), were used to prepare membranes with the aim to protect and to enhance the healing of injured skin. A mitochondrially-targeted antioxidant—MitoQ—was incorporated into the mixture of biopolymers prior to their self-association. These three-component membranes were evaluated in detail utilising surface roughness measurements, contact angle measurements, hemocompatibility, and thrombogenicity analyses. Furthermore, in vivo application of Ch/HA/MitoQ membranes was assessed on injured rabbit and rat skin utilizing histological methods. The results showed that the prepared thrombogenic Ch/HA/MitoQ membranes had higher roughness, which allowed for greater surface area for tissue membrane interaction during the healing processes, and lower cytotoxicity levels than controls. MitoQ-loaded composite membranes displayed superior healing properties in these animal models compared to control membranes.