Optimal conditions for in vitro blastogenesis of feline peripheral blood lymphocytes

A microculture technique was developed for the in vitro blastogenesis of feline lymphocytes. Blastogenesis of ficoll-diatriazoate gradient separated mononuclear cell, washed blood and whole blood were compared. In general the whole blood cultures yielded higher stimulation indices (SI) than the washed blood or separated mononuclear cell cultures.The effect of several variables on the stimulation of lymphocyte cultures was examined. A cell concentration of 3 × 10⁵ cells/well and a 1:20 dilution of washed and unwashed whole blood gave optimal stimulation with concanavalin A (Con A). Phytohaemagglutinin-P (PHA-P) did not give significant levels of stimulation. Inactivated fetal calf serum (FCS) at levels of 2.5% (for washed blood) and 5% (for separated mononuclear cell and whole blood) gave highest SI. Supplementation with FCS was preferable to autologous, homologous or horse sera for all cultures. Optimal SI was obtained in all cultures incubated for 3 days and labelled with 1 μCi tritiated thymidine (³H-TdR) for the last 16 hours. The highest SI were in the range of 70 to 105 (18,764 to 42,681 counts per minute (CPM) for separated mononuclear cell culture, 100 to 165 (28,403 to 45,334 CPM) for washed blood culture and 105 to 186 (41,076 to 69,999 CPM) for whole blood culture.     

Clinical and immunological responses of cats to feline herpesvirus type 1 infection

Cats which were challenged with feline herpesvirus type 1 developed clinical signs typical of feline viral rhinotracheitis whether or not they had been vaccinated against the disease. However, the clinical disease was less severe and of shorter duration in the vaccinated cats. After challenge, feline herpesvirus type 1 was recovered from the nostrils, oropharynx and peripheral blood leucocytes. Leucocytosis, primarily a neutrophilia, occurred initially in all the cats and was followed after clinical recovery by a mild lymphocytosis. Intradermal skin testing with feline herpesvirus type 1 and cell control antigens produced a positive delayed type skin reaction. Histology of the affected skin 72 hours after injection showed cellular infiltration, predominantly with eosinophils and neutrophils. The severity of the reaction was greater and more prolonged in the skin of the ear than in the skin of the abdomen.     

A comparison of the efficacy of two commercial Aujeszky's disease vaccines with glycoprotein-I deletion in pigs

Two commercial Aujeszky's disease vaccines, a modified killed vaccine and a sub-unit vaccine, both carrying a deletion of glycoprotein-I, were evaluated in pigs. Each vaccine was administered to two groups of four pigs, twice at 4-week intervals, with two pigs held as unvaccinated controls. All pigs were challenged with a New Zealand field isolate of Aujeszky's disease virus 3 weeks after the second vaccination. The results indicate that the sub-unit vaccine was able to protect pigs against clinical Aujeszky's disease much better than the pigs vaccinated with the modified killed vaccine when challenged with a virulent virus. However, the amount and the duration of virulent virus excretion following challenge was greater with the sub-unit vaccine than the modified killed vaccine. Pigs vaccinated with the sub-unit vaccine were shown to be latently infected following challenge. Latent infection was demonstrated by excretion of Aujeszky's disease virus from the nasal cavity after dexamethasone treatment and seroconversion of a sentinel in contact pigs to Aujeszky's disease virus.     

Generation of neuronal-like cells from umbilical cord blood-derived mesenchymal stem cells of a RFP-transgenic cloned cat

Umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) are multipotent adult stem cells, which can differentiation into cells of connective tissue and neural lineages. This study investigated the potential for neuronal differentiation of red fluorescent protein (RFP)-transgenic cat UCB-derived MSCs. The cells were cultured in pre-induction medium for 24 hr and in neuronal-induction medium for 72 hr. Immunofluorescent staining showed that 6.85% of the total cells were beta III-tubulin-positive, 3.37% were neurofilament light (NF-L)-positive and 7.04% were neurofilament medium (NF-M)-positive. A beta III-tubulin band was detected by western blot analysis. Our results demonstrate that RFP-transgenic UCB-derived MSCs can be differentiated into neuronal cells in vitro. Thus, RFP-transgenic MSCs could provide alternative tracing material for stem cell transplantation.     

Genetic diversity and toxin gene distribution among serovars of Actinobacillus pleuropneumoniae from Australian pigs

Objective

To explore the diversity among isolates of the Actinobacillus pleuropneumoniae serovars most common in Australia (serovars 1, 5, 7 and 15) and to examine the Apx toxin profiles in selected representative isolates.

Design

A total of 250 isolates selected from different farms were examined for their genotypic profiles and a subset of 122 isolates for their toxin profiles.

Methods

The isolates of serovars 1, 5, 7 and 15 selected for this study came from different farms and different Australian states and were submitted for serotyping to the reference laboratory. The overall diversity of the strains was explored with the enterobacterial repetitive intergenic consensus (ERIC) PCR and the presence of the toxin genes was investigated with a toxin PCR assay.

Results

Some degree of variation was observed in the ERIC‐PCR pattern within all four serovars, ranging from 38% to 61% genetic diversity. When looking at the toxin gene profile and, therefore, the predicted ability to produce the expected toxin pattern, one isolate each of serovars 1 (n = 20) and 7 (n = 47) and 17 isolates of serovar 15 (n = 40) showed variation to the expected gene profile.

Conclusion

The variations in toxin gene patterns, as detected by PCR, found in this study could be related to significant changes in the gene sequence or total absence of the gene. Variation in toxin gene sequences has been observed in other countries. This variation in the toxin profile could also explain possible variation in pathogenicity observed in the field.     

Effects of Processing Conditions on Nanoclay Dispersion in Starch‐Clay Nanocomposites

Wheat starch samples containing Cloisite Na+ and 30B nanoclays were extruded from a twin‐screw extruder. Moisture content, temperature, and screw speed were varied to determine their effect on nanoclay dispersion. X‐ray diffraction and transmission electron microscopy (TEM) were used to examine nanoclay intercalation and exfoliation. Moisture content had the largest effect on Cloisite Na+ dispersion, with the highest moisture sample containing exfoliated nanoclays. Meanwhile, temperature and screw speed had little effect on Cloisite Na+ dispersion. For Cloisite 30B samples, only an increase in temperature produced slight intercalation of nanoclays. This was due to the incompatibility of starch with the more hydrophobic Cloisite 30B. Also, Cloisite Na+ and 30B intercalation did not depend on specific mechanical energy. In addition, water absorbance tests indicated the Cloisite Na+ sample containing the most well‐dispersed nanoclays had the lowest water uptake.     

传染性喉气管炎病毒北京E2株gC基因的克隆及其部分序列测定

根据传染性喉气管炎病毒美国６３２株和英国Ｔｈｏｒｎｅ株ｇＣ基因的序列设计１对引物,以北京Ｅ２株为模板,用ＰＣＲ方法扩增到长度为１．９ｋｐ的片段,并将其克隆至质粒ｐＡ－Ｔ。用碱小量法制备质粒ＤＮＡ,以酶切和质粒ＰＣＲ的方法对其进行了鉴定,并以正向和反向引物测定其两翼序列,结果正向引物测出４９８个碱基,反向引物测出４９９个碱基,将所得序列输入ＧｅｎＢａｎｋ与其他毒株进行比较,结果发现其与美国６３２株的     

A new approach to enhance growth and nodulation of Acacia mangium through aeroponic culture

This work was designed to determine whether a plant culture method on non-solid media could be used as an alternative for inoculation of Acacia mangium with selected strains of Bradyrhizobium spp. A. mangium seedlings were grown and inoculated with Bradyrhizobium strain Aust13c and strain Tel2 in hydroponics, aeroponics and sand. Aeroponics was found to be the best system of the three, allowing the production of tree saplings 1 m in height after only 4 months in culture. Moreover, compared to plants grown in liquid or sand media, aeroponically grown saplings inoculated with Bradyrhizobium spp. developed a very high number of small nodules distributed all along the root system, resulting in an increase in nitrogen and chlorophyll content in plant tissues. We propose aeroponics as an alternative method to classical soil inoculation procedures for the production of hypernodulated legume tree saplings. Received: 18 July 1996