Detection and isolation of Toxoplasma gondii from fresh semen of naturally infected dogs in Southern Brazil

The aim of this study was to isolate Toxoplasma gondii and determine the viability of the parasite in fresh semen samples of clinically healthy adult dogs naturally infected. Eleven seropositive dogs with T. gondii IgG antibodies from southern Brazil were selected to confirm the presence and viability of T. gondii in fresh semen samples using in vitro isolation in Vero cell culture, polymerase chain reaction (PCR) and sequencing analysis. The presence of viable T. gondii was confirmed by in vitro isolation and PCR in five semen samples. The ITS1 region of the isolated protozoa (TG S4) was amplified and sequenced. The nucleotide sequence obtained was 99% compatible with the T. gondii DNA sequences stored in the GenBank. It has been shown that T. gondii tachyzoites may be isolated in vitro from fresh semen samples of clinically healthy dogs seropositive for T. gondii.     

Gonadotropin-releasing hormones in the African catfish: molecular forms, localization, potency and receptors

Two gonadotropin releasing hormones (GnRHs) were identified in the African catfish: chicken GnRH-II (cGnRH-II) and catfish GnRH (cfGnRH). Immunological screening of HPLC fractions from pituitary extracts indicated a third GnRH which co-eluted with lamprey GnRH-III. However, mass determination and amino acid sequencing identified this material as isotocin. This underlines the risk of identifying multiple forms of GnRH in tissue extracts on the basis of immunoreactivity in HPLC fractions. In vivo and in vitro studies demonstrated that cGnRH-II is an over 100-fold more potent gonadotropin (GTH) secretagogue than cfGnRH. This correlates with the respective receptor affinities. The presence of both GnRHs in the pituitary gland suggests that they may modulate each other's GTH release activity. Sub-threshold or low doses of cGnRH-II partly inhibited cfGnRH-induced GTH II secretion. Conversely, combinations of sub-threshold or low doses of cfGnRH with effective doses of cGnRH-II led to increases in GTH II levels similar to those induced by cGnRH-II alone. Combinations of submaximally effective dose of the 2 peptides resulted in additive effects. Hence, both GnRHs participate in the regulation of GTH II release, and their relative concentrations may determine the overall effect. Immunocytochemistry, using anti-bodies against the respective recombinant GnRH associated peptides (GAPs), as well as in situ hybridization showed that cfGnRH neurones are scattered in the ventral forebrain and project into the pituitary gland, while cGnRH-II neurones are confined to the midbrain tegmentum and without projections to the pituitary gland. Transfection experiments with GnRH receptor cDNA shows ligand activation characteristics similar to those of the native GnRH-R. Autoradiographic studies and hormone release studies indicate that GnRH-Rs in the African catfish pituitary gland are restricted to the gonadotrophs.     

Pyrrolizidine alkaloidosis of cattle associated with Senecio lautu

Summary Serious incidents of pyrrolizidine alkaloidosis of cattle in 10 herds exposed to the Australian native plant, Senecio lautus (Asteraceae), were seen in central Queensland during 1988–1992. The deaths of 226 cattle were recorded. A mean of 8% of cattle died in affected groups (range 2 to 58%). Sickness and deaths usually occurred some months after access to S lautus. Typically, affected cattle lost body condition to the point of emaciation before dying and had persistent diarrhoea. Some animals developed abnormal behaviour and died after a shorter illness. Liver specimens from affected cattle in all herds contained lesions consistent with pyrrolizidine alkaloidosis. Thin layer chromatography of extracts of blood and liver samples from cattle from 5 herds detected pyrrolic metabolites. The identity of these was confirmed by mass spectroscopy on samples from one herd. Unseasonal autumn and winter rain after a dry summer appeared to favour growth of S lautus at the expense of other pasture species. A subsequent dry period promoted consumption of S lautus and was followed by a cluster of poisoning incidents.     

Sister chromatid exchanges in calves with hereditary zinc deficiency (lethal trait A 46)

Summary

Frequencies of sister chromatid exchanges (SCEs) in cultured blood lymphocytes are rather lower than higher in calves with hereditary zinc deficiency (lethal trait A 46) than in healthy, normal cows.     

Integrated freshwater aquaculture,crop and livestock production in the Mekong delta,Vietnam: Determinants and the role of the pond

Promotion of integrated aquaculture with agriculture, including crops and livestock (IAA-farming), requires consideration of both bio-physical and socio-economic contexts. The major factors influencing the adoption of IAA-farming by households at three sites in the Mekong delta were identified. Special attention was given to the multiple roles ponds play in IAA-farming systems. Information was collected through semi-structured interviews and discussions with focus groups and key individuals. Data were analyzed using multivariate factor analysis, analysis of variance or participatory ranking methods. Three major IAA-systems were identified: (1) low-input fish farming integrated with intensive fruit production (system 1), (2) medium-input fish farming integrated with less intensive fruit production (system 2), and (3) high-input fish farming integrated with less intensive fruit production (system 3). System 1 was commonly practised in a rural fruit-dominated area with fertile soils, while systems 2 and 3 were more evident in peri-urban rice-dominated areas with less fertile soils. In the study area, only 6% of poor farmers adopted IAA-farming, while this was 42% for intermediate and 60% for rich households. Richer farmers tended to intensify fish farming and seek a more commercial orientation. The major factors why farmers did not start aquaculture were the inappropriateness of technology, insufficient land holding or poor access to extension services, limited farm management, and through a fear of conflicts associated with pesticide use on crops. The main motivations for practising IAA-farming included increased income and food for home consumption from the available farm resources while reducing environmental impacts. Further improvements to IAA-systems can be realized by strengthening nutrient recycling between different IAA-system components while enhancing farming output and safeguarding the environment.     

Nutrient concentration relationships between the fourth petiole and upper-stem of potato plants

Successfully evaluating the nutritional status of a crop during growth and development is dependent upon sampling an identifiable plant part. Consistently sampling a petiole of the same maturity in potatoes (Solanum tuberosum L.) is difficult. We evaluated the nutrient relationships between the upper-stem and the fourth petiole from Russet Burbank plants in field studies having N, P, K, Zn or Mn variables. The upper-stem was obtained by excising the stem below the sixth leaf and removing all leaves and the terminal meristem. Petole NO₃-N, P, K, Zn and Mn concentrations were from deficient to sufficient. The NO₃-N, P and K concentrations were similar in the fourth petiole and upper-stem, while the Zn concentration was 40% higher in the upper-stem. Calcium, Mg and Mn concentrations were lower in the upper-stem than in the fourth petiole. Copper and S relationships were not adequately defined. The fourth petiole’s NO₃-N, P and K diagnostic concentrations now used to monitor plant nutrient status can also be used for upper-stem samples. Zinc diagnostic concentrations should be increased, while Ca, Mg and Mn concentrations should be adjusted downward in the upper-tem. Additional data are needed to refine the Ca and Mg relationships, and to establish relationships for Cu, S and other essential nutrients. A significant advantage of using the upper-stem is the elimination of the petiole selection problem when sampling.     

Two Methods of Vitrification Followed by In Vitro Culture of the Ovine Ovary: Evaluation of the Follicular Development and Ovarian Extracellular Matrix

The aim of this study was to evaluate the influence of two vitrification techniques on the extra cellular matrix (ECM) and ovarian follicular development. The ovarian cortex was fragmented (9 mm³) and divided into six groups, viz. fresh control, cultured control, vitrified by the Ovarian Tissue Cryosystem (OTC) method, conventional solid surface vitrification (SSV) method, OTC/cultured and SSV/cultured. Follicles from all the fragments were analysed for morphology, development and viability. The ECM was evaluated based on the condition of collagen and reticular fibres and the immunolocalization of type I collagen and fibronectin. After 7 days of culture, the tissue vitrified by OTC revealed a higher percentage (p < 0.05) of morphologically normal (30.66%) and viable (60.00%) follicles when compared with those vitrified using the SSV technique (21.33% and 23.00%). In all the fragments cultured, regardless of the vitrification method, a significantly higher percentage of developing follicles was observed when compared with the non‐cultured tissue. Analysis of the type I collagen showed increased immunostaining after the in vitro culture in the vitrified fragments. In conclusion, the OTC is better for preserving the follicular viability and morphology and maintaining the integrity of the extracellular matrix components of the ovine ovary.     

Effect of pre-medication on gastroduodenoscopy in isoflurane-anesthetized cats

The pre‐medicant chosen may influence the ease with which gastroduodenoscopy (GD) is performed. The purpose of this study was to evaluate the relative ease of GD in cats under ketamine and isoflurane anesthesia after IM injection of hydromorphone (H, 0.1 mg kg^?1), hydromorphone plus glycopyrrolate (HG, 0.1 mg kg^?1 (H), 0.01 mg kg^?1 (G)), medetomidine (M, 0.03 mg kg^?1), or butorphanol (B, 0.4 mg kg^?1). Eight cats were assigned randomly to receive each treatment in a cross‐over design with at least 7 days between treatments. Twenty minutes after pre‐medication, medetomidine produced greater (p = 0.001) sedation than the other treatments when assessed, using a subjective ordinal scale. The cats were injected with ketamine (10 mg kg^?1 IM), orotracheally intubated, connected to a pediatric circle breathing system, and allowed to spontaneously breathe isoflurane in oxygen. Once end‐tidal isoflurane concentration was stable at 1.4% for 15 minutes, endoscopy was started. A single endoscopist (REG), who was unaware of the treatment used, performed all endoscopies. The endoscopist scored the difficulty of endoscopy subjectively (0–3). The significance of differences between treatments was evaluated using Friedman's test. Time for entering the stomach was 9.4 (4.7–15.9) (median (minimum–maximum)), 6.6 (5.2–11.7), 8.4 (6.3–16.5), and 7.7 (5.1–14.7) seconds and for entering the duodenum from the stomach was 20.5 (13.8–40.9), 18.2 (10.3–39.8), 20.2 (16.2–119.5), and 22.2 (11.8–83.8) seconds for H, HG, M, and B treatments, respectively. There were no significant differences in the time for, or difficulty of, endoscopy. We conclude that any of these drugs can be used satisfactorily at the doses and combinations tested to pre‐medicate cats prior to general anesthesia for GD.