The action of two ethyl carbamates on acetylcholinesterase and reproductive organs of Rhipicephalus microplus.

The effects produced by the new synthetic carbamates ethyl-(4-bromophenyl) carbamate and ethyl-(4-chlorophenyl) carbamate on the acetylcholinesterase (AChE) activity, egg structure and reproductive organs of two Rhipicephalus microplus strains were evaluated. Inhibition kinetic parameters showed that the studied carbamates are weak inhibitors and have a low affinity for R. microplus AChE. Histologically, in oocytes from carbamate-treated engorged female ticks, a loss of shape, cytoplasmic vacuoles, decreased chorion deposition, alterations in cytoplasmic granularity and irregular membranes were observed. In oocyte germinal vesicles, a loss of shape, nucleolar fragmentation and membrane alterations with degenerative signs were observed. The ovarian epithelium was vacuolated, flattened, eroded and contained pyknotic nuclei. These alterations were observed from the first day and persisted and increased in severity until day 7 post-treatment. The ovaries from carbamate-treated ticks had fewer stage IV-V oocytes and more stage I-II oocytes. Additionally, eggs produced by the treated ticks had a modified appearance, decreased size, a reduced superficial waxy layer and a loss of viability. The results of this study show that the effects of carbamates on R. microplus were independent of AChE inhibition and show that the morphological alterations in the reproductive organs were due to carbamate actions on the vitellogenesis and viability of the ovarian cells.

A study of the process of apoptosis in animals infected with the contagious ecthyma virus.

Contagious ecthyma virus (CEV) is a disease caused by a parapoxvirus, also is a potent genetic carrier with the capacity for regulating apoptosis in the cells of infected skin, a mechanism that serves for evading the immune response of the host. It has been suggested that the virus may remain in the skin and be able to cause repeated infections in the same flock. The effect of infection as well as the presence of contagious ecthyma virus was evaluated in terms of lesions and apoptosis in the skin of animals, infected both naturally and experimentally. Samples used were obtained from a naturally infected sheep, 5 goats inoculated with CEV and a negative control. Samples obtained were longitudinally sectioned and processed using photon and electron microscopy, and embedded in paraffin and araldite. Samples embedded in paraffin were sectioned in 5 microm of thickness and dyed with orange eosin-hematoxilin G and Gomori's trichrom stain, apoptosis was demonstrated by the TUNEL assay, the viral antigen was revealed using polyclonal antibodies, and the presence of lymphocytes CD4+ and CD8+, with monoclonal antibodies. The samples processed in resin were cut to obtain semi-fine sections and dyed with toluidine blue-borax, and the ultra-fine sections were impregnated with lead citrate and uranyl acetate. Observations were similar in both, the natural infected animal and the experimental group. Infiltration was observed as well as images suggestive of a process of apoptosis. The TUNEL assay demonstrated that the number of epithelial cells undergoing apoptosis diminished during the process and increased among defense cells, until they almost disappeared at the beginning of healing. Cells undergoing apoptosis were located near the sebaceous glands and pilose follicles. The infiltrated lymphocytes gradually diminished. The viral antigen was observed in cells with morphology suggestive of apoptosis, located in sebaceous glands and pilose follicles. Using electron microscopy, cells with morphology compatible with that of lymphocytes were observed to be undergoing apoptosis, but there was little evidence of viral particles.

Rat embryo quality and production efficiency are dependent on gonadotrophin dose in superovulatory treatments.

The present study was performed to optimize a superovulation protocol in rats in order to produce a large number of good-quality embryos suitable to develop rat embryonic stem (rES) cells. We first evaluated the ovulation kinetics of three rat strains: Wistar, Fisher and ACI/N. Animals (n=30 per strain) were treated with 50 IU of pregnant mare serum gonadotrophin (PMSG), and ovulation was induced with 50 IU of human chorionic gonadotrophin (hCG) 50 h apart. Next, we evaluated the dose-response curves of PMSG and hCG in Wistar rats in order to obtain the highest number of embryos. The parameters evaluated for superovulation efficiency were: percentage of mated females, percentage of pregnant females and the average number of embryos collected per female. The results of these experiments suggested that the best dose combination was 50 IU for each hormone. Subsequent experiments, again with Wistar rats, were designed to test which of four hormonal combination treatments (30/30, 30/50, 50/30, and 50/50 IU of PMSG/hCG) will produce the largest numbers of good-quality embryos. Embryo quality was evaluated by embryo development uniformity, embryo morphology, embryo survival in an in vitro culture and embryo ability to generate rES-like cells. Results from these experiments showed that 30/50 IU of PMSG/hCG was the treatment that induced the best embryo quality. In conclusion, our results indicated that, in Wistar rats, the most appropriate hormonal combination dose for superovulation protocols with high number of good-quality embryos was 30 IU of PMSG and 50 IU of hCG given 50 h apart. We are performing further studies with rES-like cells produced with the present methodology to evaluate if they are able to participate in the production of germ-line chimeras.

[Identification of caprine arthritis encephalitis virus using histopathological, immunohistochemica, and ultrastructural examination of tissues from seropositive goats in Mexico]. / Identificación del virus de la artritis encefalitis caprina mediante el estudio histopatológico, inmunohistoquímico y ultraestructural, en tejidos de cabras seropositivas en México.

This study demonstrated the presence of viral particles suggestive of arthritis-encephalitis virus through the clinic, serologic, pathologic, immunohistochemic and ultrastructural studies in dairy goats. In the postmortem studies the tissues used were: synovial membrane, lungs and mammary gland from goats with clinical signs characteristic of the disease and positive for serum antibodies to the virus.