Immunological basis of septal fibrosis of the liver in Capillaria hepatica-infected rats

Rats infected with the helminth Capillaria hepatica regularly develop septal fibrosis of the liver similar to that induced by repeated ip injections of pig serum. Fibrosis starts when the focal parasitic lesions begin to show signs of resorption, thus suggesting an immunologically mediated pathogenesis of this fibrosis. To explore this possibility, the development of C. hepatica-related hepatic fibrosis was observed in rats exposed to worm antigens from the first neonatal day onward. Wistar rats (150 g) were either injected ip with an extract of C. hepatica eggs (protein concentration: 1 mg/ml) or received immature eggs by gavage from the first neonatal day until adult life and were then infected with 500 embryonated eggs. Changes were monitored on the basis of serum levels of anti-worm antibodies and hepatic histopathology. Rats submitted to immunological oral tolerance markedly suppressed C. hepatica-related serum antibodies and septal fibrosis of the liver when infected with the helminth later on. Tolerance trials with ip injections of worm antigens gave essentially negative results. The partial suppression of septal fibrosis of the liver after the induction of immunological tolerance to C. hepatica antigens in rats indicates an immunological basis for the fibrosis and emphasizes the importance of immunological factors in the pathogenesis of hepatic fibrosis.

Production of a cloned calf from a fetal fibroblast cell line

The present study examined the in vitro and in vivo development of bovine nuclear-transferred embryos. A bovine fetal fibroblast culture was established and used as nucleus donor. Slaughterhouse oocytes were matured in vitro for 18 h before enucleation. Enucleated oocytes were fused with fetal fibroblasts with an electric stimulus and treated with cytochalasin D and cycloheximide for 1 h followed by cycloheximide alone for 4 h. Reconstructed embryos were cultured for 7-9 days and those which developed to blastocysts were transferred to recipient cows. Of 191 enucleated oocytes, 83 (43.5%) were successfully fused and 24 (28.9%) developed to blastocysts. Eighteen freshly cloned blastocysts were transferred to 14 recipients, 5 (27.8%) of which were pregnant on day 35 and 3 (16.7%) on day 90. Of the three cows that reached the third trimester, one recipient died of hydrallantois 2 months before term, one aborted fetus was recovered at 8 months of gestation, and one delivered by cesarian section a healthy cloned calf. Today, the cloned calf is 15 months old and presents normal body development (378 kg) and sexual behavior (libido and semen characteristics).

Female novelty and the courtship behavior of male guinea pigs (Cavia porcellus)

In several rodent species, an increase or recovery of sexual behavior can be observed when sexually satiated males are placed in contact with a novel mate. In order to assess the influence of female novelty on the courtship behavior of guinea pigs (Cavia porcellus), four adult males were observed during four daily 15-min sessions while interacting with the same pregnant female (same-female sessions). A new female was presented during the fifth session (switched-female session). The duration of behavioral categories was obtained from videotape records using an observational software. From the first to the second session, all males decreased the time allocated to investigating (sniffing and licking), following, and mounting the female, and that response did not recover by the end of the same-female sessions. No similar decreasing tendencies were detected in the circling or rumba categories. A marked increase of investigating occurred in all males from the last same-female session (8.1, 11.9, 15.1 and 17.3 percent session time) to the switched-female one (16.4, 18.4, 37.1 and 28.9 percent session time, respectively). Increases in following and circling were recorded in three of four males, and full-blown recovery of mounting in one male. No consistent changes in the females' responses to males (following or attacking) were observed throughout testing. These results are consistent with the hypothesis that guinea pig males recognize individual females and that courtship responses may suffer a habituation/recovery process controlled by mate novelty.