Contrasting effects of heat shock during in vitro maturation on development of in vitro‐fertilized and parthenogenetic bovine embryos

This study investigated the influence of heat shock during in vitro maturation on embryo development following in vitro fertilization (IVF) or parthenogenesis (Part). Immature bovine cumulus–oocyte complexes were exposed to heat shock (41.0°C) during the first 12 hr of in vitro maturation (IVM), followed by 12 hr at 38.5°C. Control group consisted of in vitro maturation for 24 hr at 38.5°C. Oocytes were in vitro‐fertilized or activated with ionomycin and cultured in vitro for 192 hr post‐in vitro insemination or parthenogenetic activation (hpia). There was an interaction (p < .01) between temperature of IVM and method of oocyte activation (IVF or Part) for cleavage at 48 hpia. Heat shock had a negative impact (p < .01) on cleavage of IVF embryos, whereas no (p > .05) effect was found in the Part embryos. Embryo development towards blastocyst stage at 168 and 192 hpia decreased in both IVF and Part embryos derived from heat‐shocked oocytes. Heat shock increased (p < .05) the apoptotic index in Part blastocysts, but no effect (p > .05) was found in IVF counterparts. Heat shock also down‐regulated the expression of AQP3 (p < .01) and up‐regulated the expression of HSP70.1 (p < .01) in Part blastocysts, whereas it down‐regulated the expression of ATP1A1 (p < .05) in IVF blastocysts. In conclusion, the effects of heat shock during IVM on early embryo cleavage and blastocyst apoptosis are influenced by the method of oocyte activation and expression of some genes can be disturbed in embryos derived from heat‐shocked oocytes.     

Photosynthesis of field-grown Arracacha (Arracacia xanthorriza Bancroft) cultivars in relation to root-yield

There has been limited research on measuring potential differences in leaf gas exchange of Arracacha (Peruvian parsnip, Arracacia xanthorriza Bancroft) cultivars, as affected by different environments, as well as its relation to storage root-yield. The present paper reports field measurements of leaf CO₂ assimilation rates (A) for five contrasting cultivars grown at two different high-altitude locations. Using a design of plots chosen at random with three repetitions, commercial root production was determined in the two locations at different altitude (1580 and 1930 m). Daily leaf gas exchange was repeatedly monitored with a portable open-mode infrared gas analyzer at different times in both locations during the growth cycle. Root-yield, leaf area and dry weight were measured. Significant differences in leaf photosynthetic rate and in specific leaf area (SLA) were observed among cultivars. Cultivars with high SLA, had high CO₂ assimilation. Mean (A_n) and total (A_tot) of CO₂ assimilation and SLA were significantly correlated with storage root-yield across cultivars and locations. The three cultivars with the greatest commercial root production also had the highest maximum values for A and the highest specific leaf area, indicating that these two parameters can be used to select for highly productive cultivars of A. xanthorriza.     

Effective plasma alfaxalone concentration to produce immobility in male neutered cats

Objective

To determine the effective plasma alfaxalone concentration for the production of immobility in cats.

Specific detection of Histomonas meleagridis in turkeys by a PCR assay with an internal amplification control

Histomoniasis or blackhead is a disease of gallinaceous birds, caused by the protozoon Histomonas meleagridis. Since traditional diagnostics for the detection of this disease are complex and far less sensitive than molecular tools, a PCR would provide a more rapid and sensitive alternative. However, intestinal material and droppings, which are preferably used in epidemiological studies of histomoniasis, often contain PCR inhibitory substances. To detect these false negative results, the use of an internal amplification control is essential. Nevertheless, the recently developed PCR tests lack this internal control. Therefore, a new PCR assay with H. meleagridis specific primers was developed which does include an internal amplification control. The diagnostic value of the PCR assay was evaluated in comparison to three other conventional H. meleagridis specific PCR tests (HIS5, HM1 and HM2). None of the organ samples originating from uninfected turkeys, showed positive PCR results in any of the tests. Among the lesion-positive, inhibition-free samples, 95.4% were positive by our PCR assay, while only 50, 66.7 and 83.3% of the lesion-positive organs tested positive by the HM1, the HIS5 and the HM2 PCR respectively. In conclusion, our PCR offers the use of the internal control to detect false negative results and an increased sensitivity, and thus should be useful for routine diagnosis of H. meleagridis in poultry.     

Comparison of serological assays for the diagnosis of canine visceral leishmaniasis in animals presenting different clinical manifestations

Three serological methods, indirect fluorescent immunoassay (IFI), enzyme-linked immunosorbent assay (ELISA) and direct agglutination test (DAT) that are commonly employed in the diagnosis of canine visceral leishmaniasis (CVL), have been assessed. A total of 234 domestic dogs, drawn from an area in the municipality of Belo Horizonte, Minas Gerais, Brazil, endemic for visceral leishmaniasis, were submitted to clinical and parasitological examinations and serological assay. Sera collected from confirmed non-infected dogs (n=20), and from dogs with other parasitic diseases including Trypanosoma cruzi (n=7), Leishmania braziliensis (n=5), Toxoplasma gondii (n=5) and Ehrlichia canis (n=3), were also included in the study. IFI presented a lower sensitivity (72%) than ELISA (95%), although the specificities of these assays were low (52 and 64%, respectively) and both exhibited cross-reactivity with sera from dogs infected with T. cruzi, L. braziliensis and E. canis. In contrast, DAT exhibited a high sensitivity (93%) and a high specificity (95%) and cross-reacted with only one serum sample derived from an E. canis-infected dog. The reproducibilities of the ELISA and DAT assays were excellent, whilst that of IFI was considered to be acceptable. The results produced by ELISA and DAT were in complete agreement, those between ELISA and IFI were at an acceptable level of agreement, whilst the concurrence between the IFI and DAT results were either acceptable or poor depending on the clinical conditions of the group of dogs examined. Since there is no readily accessible method for the diagnosis of CVL that offers 100% specificity and sensitivity, the choice of technique employed must depend on the aim of the investigation.     

Gastrointestinal protozoa in non-human primates of four zoological gardens in Belgium

Gastrointestinal parasites are important infectious causes of diarrhoea in captive non-human primates (NHP). However, prevalence data of gastrointestinal parasites in zoological gardens are scarce. Therefore, a cross-sectional survey was conducted to estimate the occurrence of gastrointestinal parasites in NHP of four zoological gardens in Belgium. Between August 2004 and April 2006, 910 faecal samples were collected from 222 animals housed in 39 groups. The 31 species involved were representatives of prosimians, New World (NW) monkeys, Old World (OW) monkeys and apes. Because individual sampling was impossible, a statistical simulation was performed to estimate a sufficient sample size. All samples were microscopically examined after an acetic acid-ether concentration. Differences in host species susceptibility were examined by non-parametric tests. Entamoeba spp. (44%) and Giardia spp. (41%) were the most prevalent species. Other parasites detected were Endolimax nana (36%), Chilomastix mesnili (21%), Balantidium coli (13%), Trichuris spp. (10%), Iodamoeba bütschlii (5%) and Strongyloides spp. (5%). Parasites for which a significant difference in susceptibility at the level of host taxonomy was noted were Entamoeba spp. (p<0.001) and C. mesnili (p<0.05). Samples containing Entamoeba spp. were the most prevalent in OW monkeys (p<0.0083). Samples collected from OW monkeys contained the highest number of parasite species (p<0.0083).     

Immunodiagnosis of current fasciolosis in sheep naturally exposed to Fasciola hepatica by using a 2.9 kDa recombinant protein

A 2.9 kDa recombinant-Fasciola hepatica protein (FhrAPS) was employed to estimate the prevalence of fasciolosis in sheep maintained under field conditions. For this purpose, 340 samples with known status in relation to fasciolosis by using a direct-ELISA and the coprological sedimentation were used. These samples were analysed by using an indirect-ELISA (iELISA) and the FhrAPS recombinant protein and excretory/secretory antigens (FhES) of this trematode. Current fasciolosis (CF) was named when results were positive to antigenemia and/or coprology. Out of 198 sheep with current fasciolosis, 68% were positive to the FhrAPS-ELISA test and 53% to the FhES. We observed 14% of the CF-neg sheep were positive to the FhrAPS, whereas this percentage was 52% with the FhES. A significant correlation between FhrAPS and current fasciolosis was obtained (r2=0.513, p=0.001). We concluded that the FhrAPS provides a more suitable antigen than FhES for developing field trials to know the prevalence of early and current fasciolosis.     

Irrigation effects on elephant grass morphology,and its genotype-dependent responses

This study hypothesised that different elephant grass genotypes respond differently in terms of their morphological development to irrigation. The objective of this study was to evaluate how water availability could affect the morphological development of different genotypes of elephant grass. The treatments consisted of four genotypes of elephant grass [Cenchrus purpureus (Schumach.) Morrone], managed under irrigation or not, during a two-year field trial. The experiment was arranged in a randomised block design in a split-plot, with four replicates per treatment (n = 4). Between the genotypes, two of them were classified as tall-sized (IRI 381 and Elephant B), and two as dwarfs (Taiwan A-146 2.37 and Mott). A three-way interaction between season, irrigation, and genotype affected the variables plant height, stem diameter, number of dead tillers, light interception (LI), and leaf area index (LAI) (p < .05). The morphological development of all genotypes was negatively impacted by the dry season. All genotypes grew taller during the rainy season (p < .05) and had a greater light interception (62%–80%) compared to the dry period (28%–59%). The genotype Mott, showed comparable LI and LAI to the tall-sized genotypes, whilst Taiwan A-146 2.37 was characterized by the lowest values, despite being the genotype with the greatest tiller density (60 tillers m⁻²) (p < .05). The use of irrigation mitigated the negative effects of the dry season on the plants, however, the type and size (tall vs. dwarf) of the elephant grass genotypes defined the extent of the responses to the use of the irrigation during the dry period.     

Limnology of Macrobrachium amazonicum grow‐out ponds subject to high inflow of nutrient‐rich water and different stocking and harvest management

We evaluated the water characteristics and particle sedimentation in Macrobrachium amazonicum (Heller 1862) grow‐out ponds supplied with a high inflow of nutrient‐rich water. Prawns were subject to different stocking and harvesting strategies: upper‐graded juveniles, lower‐graded juveniles, non‐graded juveniles+selective harvesting and traditional farming (non‐grading juveniles and total harvest only). Dissolved oxygen, afternoon N‐ammonia and N‐nitrate and soluble orthophosphate were lower in the ponds in comparison with inflow water through the rearing cycle. Ponds stocked with the upper population fraction of graded prawns showed higher turbidity, total suspended solids and total Kjeldahl nitrogen than the remaining treatments. An increase in the chemical oxygen demand:biochemical oxygen demand ratio from inlet (4.9) to pond (7.1–8.0) waters indicated a non‐readily biodegradable fraction enhancement in ponds. The sedimentation mean rate ranged from 0.08 to 0.16 mm day^?1 and sediment contained >80% of organic matter. The major factors affecting pond ecosystem dynamic were the organic load (due to primary production and feed addition) and bioturbation caused by stocking larger animals. Data suggest that M. amazonicum grow‐out in ponds subjected to a high inflow of nutrient‐rich water produce changes in the water properties, huge accumulation of organic sediment at the pond bottom and non‐readily biodegradable material in the water column. However, the water quality remains suitable for aquaculture purposes. Therefore, nutrient‐rich waters, when available, may represent a source of unpaid nutrients, which may be incorporated into economically valued biomass if managed properly.