The transferrin receptor of Actinobacillus pleuropneumoniae: quantitation of expression and structural characterization using a peptide-specific monoclonal antibody

When Actinobacillus pleuropneumoniae (A. pp) is grown under iron-restricted conditions in vitro, transferrin binding proteins (Tbps) are induced. The functional transferrin receptor of A. pp is composed of two outer membrane proteins (Tbp1 and Tbp2) and shows an exquisite specificity for porcine transferrin. This complex was studied using a monoclonal antibody (Mab 1.48) raised against a synthetic peptide corresponding to a hydrophilic domain of Tbp2 common to several A. pp serotypes. The antibody reacted specifically with a 60-70kDa Tbp2-antigen found in all serotypes of A. pp obtained from iron-restricted culture. It was found that Tbp2 was not expressed in iron replete medium by any serotype except serotypes 5a, 5b and 6 where a weak expression was seen. There was a weak expression of related antigens in Actinobacillus indolicus and Actinobacillus suis under iron-depleted conditions while no similar antigens were detected with the Mab in iron-starved Actinobacillus lignieresii, Actinobacillus porcinus, Actinobacillus minor, Haemophilus influenzae, and Haemophilus parasuis.Using an enzyme-linked immunosorbent assay (ELISA) based on the Mab 1.48, Tbp2 could be detected in both recombinant E. coli expressing Tbp2 and in wild type A. pp grown under iron restricted conditions. The subcellular location of Tbp2 in A. pp was studied by immunoelectron microscopy using the Mab 1.48. Interestingly, all antibody binding was found inside the A. pp cells, while Tbp2 expressed in recombinant E. coli was found both in the cytosol and on the outer membrane. These results indicate that the Mab 1.48-reactive epitope of Tbp2 is surface exposed when it is expressed without Tbp1 in E. coli while the inaccessibility of this epitope of Tbp2 in A. pp could be due to shading by the association between Tbp2 and Tbp1.     

5alpha-androstenone in fat from boars selected for rate of gain and thickness of back fat, and from boars used in artificial insemination service.

Large variations in the level of 5α-androstenone in fat from different boars have been found. No significant difference in the level of 5α-androstenone was detected in fat from boars selected for high rate of gain and low back fat (HP-line), low rate of gain and high degree of fatness (LP-line) and a control group maintained without deliberate selection (GL-line). In boars used in artificial insemination service relatively high levels of 5α-androstenone in fat were observed, and in these animals a significant (P < 0.05) positive regression of 5α-androstenone level on age was found. Positive but non-significant regression coefficients were found between number of services which the boars had performed and level of 5α-androstenone in fat from the same animals.     

A New Species of Tatera from Tanzania with a Description of its Life History and Habits Studffid in Captivity

This study documents the fauna associated with two common comatulid crinoid species, Comanthus wahlbergi and Tropiometra carinata, in False Bay, South Africa, and describes the patterns of infestation of obligate associate species. A total of 11 invertebrate species was found associated with one or both crinoids. Of these, three were considered obligate: the myzostomidans, Myzostoma fuscomaculatum and Myzostoma n.sp., and the shrimp, Hippolyte catagrapha, all of which only occurred on T. carinata. Both frequency and density of infestation were higher for the two myzostomes than for the shrimp. The majority of crinoids infested with myzostomes hosted two or more individuals, while H. catagrapha usually occurred singly. A total of 67.5% of all T. carinata collected were infested by symbionts. Of these 45% hosted only one species, 17% hosted two species and 5.8% hosted all three. Most M. fuscomaculatum (85.2%) and H. catagrapha (82.1%) matched their hosts’ colouring, while Myzostoma n. sp. were all yellowish incolour. Infestation by Myzostoma n. sp. increased in both frequency and density with depth. All three obligate symbiont species are new to science, illustrating the biodiversity that can still be uncovered by investigating new niches.     

Effects of hCG Stimulation on Hepatic Activities of Cytochromes P4502E1 and P4502A in Pubertal Male Pigs

The effects of human chorionic gonadotropin (hCG) stimulation on fat skatole concentrations and hepatic activities of cytochromes P4502E1 (CYP2E1) and P4502A (CYP2A) were studied in Landrace and Duroc breeds of entire male pigs. Pigs were divided into four groups: two control groups of each breed, without hCG stimulation (n = 20 for each breed), and two experimental groups of each breed, with hCG stimulation (n = 18 for each breed). Pigs were slaughtered 3 days after hCG stimulation and activities of CYP2E1 and CYP2A were measured in liver homogenate. Activities of both CYP2E1 and CYP2A were lower in hCG‐stimulated pigs than control pigs for both Landrace (p = 0.005 for CYP2E1, p = 0.016 for CYP2A) and Duroc breeds (p = 0.003 for CYP2E1, p = 0.001 for CYP2A), and skatole concentrations in fat were higher in the hCG‐stimulated pigs of both breeds (p < 0.01). For both control and hCG‐stimulated groups, Duroc pigs had lower skatole concentrations than Landrace pigs (p = 0.001 for both groups). The activity of CYP2E1 did not differ significantly between breeds in either the control group or the experimental group (p = 0.233 for control pigs and p = 0.210 for experimental pigs). However, whereas CYP2A activity did not differ significantly between breeds in the control groups (p = 0.181 for CYP2A), in the hCG‐stimulated groups, CYP2A activity was lower in Duroc pigs than in Landrace (p = 0.011). Based on these findings, we conclude that hCG stimulation can suppress hepatic CYP2E1 and CYP2A activities, probably through an increase in the levels of testicular steroids. Between‐breed variations in skatole levels in fat were not related to the activities of CYP2E1 and CYP2A.     

Linkage between the H and 6-PGD loci in pigs

The designation H stands for a blood group system and its corresponding chromosomal locus in pigs. The system includes multiple alleles, but merely two of these, H^a and H^c, were involved in the present investigation. The two alleles are co-dominant and form a closed system in the Duroc breed (Andre-sen 1963, 1964). The results of the present study using pigs of the Danish landrace breed and particularly the Duroc breed have shown that electrophoretic variants of the enzyme 6-phospho-gluconate dehydrogenase (6-PGD) in the erythrocytes likewise are determined by two alternative alleles, A and B, in pigs of both breeds. Thus, in agreement with observations by Saison (1968), who studied various other breeds and their crosses, three electrophoretic patterns were observed among the pigs studied. The three patterns or types appear as bands in the starch-gel after the addition of substrate. They are designated as A, AB and B. They correspond to the genotypes AA, AB and BB.     

Development and evaluation of a mixed long-chain lipopolysaccharide based ELISA for serological surveillance of infection with Actinobacillus pleuropneumoniae serotypes 2, 6 and 12 in pig herds

The objective was to develop an enzyme-linked immunosorbent assay (ELISA) for simultaneous detection of antibodies against Actinobacillus pleuropneumoniae (Ap) serotypes 2, 6 and 12. The assay was designated MIX-ELISA. Lipopolysaccharide (LPS) from Ap serotypes 2, 6 and 12 was purified using hot phenol-water extraction followed by fractionation by size-exclusion chromatography. A mixture of fractions containing molecules with molecular weight above 50 kDa from all three serotypes was used as antigen. The MIX-ELISA was evaluated with sera from pigs experimentally infected with the serotypes 1, 2, 5b, 6, 7, 8, 10 and 12 of Ap biotype 1. In addition to reaction with sera from pigs inoculated with Ap serotypes 2, 6 and 12, reaction was observed with sera from pigs inoculated with serotype 8. Furthermore, the sensitivity and specificity of the test on a herd level were evaluated with sera from herds naturally infected with serotypes 2, 6 or 12 and with sera from herds free of infection with any Ap serotype of biotype 1. The ELISA showed a high herd sensitivity (0.98; 95% confidence interval: 0.89-1.00) and specificity (0.95; 0.88-0.99). The high diagnostic sensitivity and specificity of the assay indicate that screening of herds for Ap infection can be performed using this ELISA. Efficient serological surveillance can be achieved by using such mixed antigen ELISAs coated with size-selected LPS-antigens from the most prevalent serotypes.     

Forest loss and matrix composition are the major drivers shaping dung beetle assemblages in a fragmented rainforest

Context

Identifying the drivers shaping biological assemblages in fragmented tropical landscapes is critical for designing effective conservation strategies. It is still unclear, however, whether tropical biodiversity is more strongly affected by forest loss, by its spatial configuration or by matrix composition across different spatial scales.

Objectives

Assessing the relative influence of forest patch and landscape attributes on dung beetle assemblages in the fragmented Lacandona rainforest, Mexico.

Methods

Using a multimodel inference approach we tested the relative impact of forest patch size and landscape forest cover (measures of forest amount at the patch and landscape scales, respectively), patch shape and isolation (forest configuration indices at the patch scale), forest fragmentation (forest configuration index at the landscape scale), and matrix composition on the diversity, abundance and biomass of dung beetles.

Results

Patch size, landscape forest cover and matrix composition were the best predictors of dung beetle assemblages. Species richness, beetle abundance, and biomass decreased in smaller patches surrounded by a lower percentage of forest cover, and in landscapes dominated by open-area matrices. Community evenness also increased under these conditions due to the loss of rare species.

Conclusions

Forest loss at the patch and landscape levels and matrix composition show a larger impact on dung beetles than forest spatial configuration. To preserve dung beetle assemblages, and their key functional roles in the ecosystem, conservation initiatives should prioritize a reduction in deforestation and an increase in the heterogeneity of the matrix surrounding forest remnants.

     

Prevention of edema disease in pigs by passive immunization.

The effect of treatment with verotoxin 2e (VT2e) specific antiserum was evaluated in 3 Danish pig herds with edema disease (ED). The antiserum was prepared by immunizing horses with a VT2e toxoid. The study was performed as a randomized blind field trial with parallel treatment and control groups. There were approximately 50 piglets in each group in each of the 3 herds and 741 piglets were included in the study (244 from herd A, 249 from herd B, and 247 from herd C). Treatment groups received 2, 4, or 6 mL anti-VT2e serum intramuscularly the day before weaning. Control groups were treated with 6 mL normal horse serum or 6 mL RPMI 1640 medium as placebo. All pigs that died in the trial period (1 d before weaning to 44 d after weaning) were examined pathologically and microbiologically. Mortality due to ED, mortality due to other causes, and adverse effects due to treatment were recorded. As there was no mortality due to ED, herd B was excluded from statistical calculations on mortality. The content of horse antibodies specific to VT2e in serum from pigs was analyzed in an indirect ELISA. A higher dose of anti-VT2e serum was reflected in higher optical density values in the indirect ELISA. Transient adverse reactions, seen as vomiting, ataxia, and cyanosis, occurred shortly after the injection of horse serum in 1.5% of the pigs, and one pig died. There were no statistically significant differences in mortality due to other causes among the 3 treatment groups in herds A and C. Only pigs from which F18+, VT2e+, ST-, LT- hemolytic E. coli (0139 or O-rough) was isolated were diagnosed as dead due to ED. Deaths due to ED in the control groups were 8.1% and 12.0% in herds A and C, respectively, compared with 0% and 0.7% in the corresponding serum groups. The difference between treatment and control groups was statistically significant (P<0.0001). It was not possible to establish an effect of dose (2, 4, or 6 mL) of anti-VT2e serum, because only one pig died of ED in the treatment groups. It was concluded that passive immunization by intramuscular injection of a VT2e-specific antiserum can be used for protecting piglets against ED.     

Beitrag zur Zyklussynchronisation bei Rindern mit dem Prostaglandin-Analog "Reprodin®"

In den Jahren 1978/79 und 1979/80 wurde 103 Färsen der Rasse "Deutsche Rotbunte" das Prostaglandin-Analog "Reprodin®" zum Zwecke der Zyklussynchronisation verabreicht. 37 Färsen der Versuchsgruppe I erhielten zweimal im Abstand von 11 Tagen 2 ml (= 15 mg) Reprodin® i. m., 37 weitere Färsen zu den gleichen Zeitpunkten 2 ml Plazebo i. m. Die Besamung erfolgte bei allen 74 Färsen 48 und 72 Stunden nach der 2. Injektion. Eine weitere Besamung wurde bei den Kontroll-tieren, die innerhalb von 3 Wochen nach der terminierten Insemination in Brunst gekommen waren, vorgenommen. Das Erstbesamungsergebnis der Versuchsfarsen be-trug 40,5 % und das der Kontrolltiere 35, l %.
Den 66 Versuchsfärsen der Versuchsgruppe II applizierten wir 2 ml Reprodin® intramuskulär. 53 Färsen (80,3 %) wurden nach dieser einmaligen Injektion nach Auftre-ten deutlicher Brunstsymptome zweimal besamt, wobei die erste Besamung bei 6 Tieren (11,3 %) nach 48 Stunden, bei 46 Tieren (86,8 %) nach 72 Stunden und bei einem Tier (1,9%) nach 96 Stunden erfolgte. Die 13 Färsen, die zu diesem Zeit-punkt keine äußeren Brunstsymptome zeigten, erhielten 11 Tage nach der 1. Appli-kation noch einmal 15 mg Reprodin® und wurden 60 und 84 Stunden später besamt. Das Erstbesamungsergebnis betrug nach einer einmaligen Reprodin®-Gabe 67,9 % und nach einer zweimaligen 69,2 %. Ein negativer Einfluß auf die Zykluslänge konnte nach Verabreichung von Reprodin® nicht festgestellt werden.