Prevalence of tail lesions in Swiss finishing pigs

INTRODUCTION

Tail biting and lesions are common problems in modern pig production. In 2008 tail docking to prevent tail biting was banned in Switzerland. Since then pigs have been raised with intact tails. This study aimed to assess the current prevalence of tail lesions at Swiss abattoirs and comparing abattoir data with farm-specific data regarding potential risk factors for tail lesions. Data collection was performed in repetitive cycles of two weeks at four abattoirs during all consecutive seasons of one year. Gender, tail length and the tail tip condition were evaluated among other parameters. During 32 weeks in total, 195 704 pigs from 6112 batches from 2510 herds were evaluated. Overall, 63,2 % of the animals included in the analysis were slaughtered with a complete tail (lowest tail length score [TLS]), whereas 36,8 % showed a partial or total loss of the tail. The condition of the tail tip (tail tip condition score [TTCS]) was judged as being intact in 63,0 %, as a healed lesion in 23,7 %, an acute lesion in 1,3 % and a chronic lesion in 12,0 % of all cases. Male animals had significantly higher values for TLS and TTCS than female animals (P ≤ 0,05). TLS values were significantly higher in winter than in spring and summer (P < 0,001). TTCS values were significantly higher in fall than in spring and summer. TLS and TTCS values differed significantly (P < 0,001) between the four abattoirs. Only few significant correlations were found between values of TLS and TTCS and farm-specific data. Recording tail lesions at abattoirs is an accurate method to investigate the prevalence of tail lesions in fattening pigs. However, to monitor animal welfare on herd level, this method is very labor intensive. Moreover, data on tail lesions collected at the abattoir cannot replace veterinary on-farm examination for risk factor identification.

Synthesis, characterization, and application of cy-dye- and alexa-dye-labeled hongotoxin(1) analogues. The first high affinity fluorescence probes for voltage-gated K+ channels

Hongotoxin(1) (HgTX(1)), a 39-residue peptide recently isolated from the venom of Centruroides limbatus, blocks the voltage-gated K+ channels K(v)1.1, K(v)1.2, and K(v)1.3 at picomolar toxin concentrations (Koschak, A., Bugianesi, R. M., Mitterdorfer, J., Kaczorowski, G. J., Garcia, M. L., and Knaus, H. G. (1998) J. Biol. Chem. 273, 2639-2644). In this report, we determine the three-dimensional structure of HgTX(1) using NMR spectroscopy (PDB-code: 1HLY). HgTX(1) was found to possess a structure similar to previously characterized K+ channel toxins (e.g. margatoxin) consisting of a three-stranded antiparallel beta-sheet (residues 2-4, 26-30, and 33-37) and a helical conformation (part 3(10) helix and part alpha helix; residues 10-20). Due to the importance of residue Lys-28 for high-affinity interaction with the respective channels, lysine-reactive fluorescence dyes cannot be used to label wild-type HgTX(1). On the basis of previous studies (see above) and our NMR data, a HgTX(1) mutant (HgTX(1)-A19C) was engineered, expressed, and purified. HgTX(1)-A19C-SH was labeled using sulfhydryl-reactive Cy3-, Cy5-, and Alexa-dyes. Pharmacological characterization of fluorescently labeled HgTX(1)-A19C in radioligand binding studies indicated that these hongotoxin(1) analogues retain high-affinity for voltage-gated K+ channels and a respective pharmacological profile. Cy3- and Alexa-dye-labeled hongotoxin(1) analogues were used to investigate the localization of K+ channels in brain sections. The distribution of toxin binding closely follows the distribution of K(v)1.2 immunoreactivity with the highest expression levels in the cerebellar Purkinje cell layer. Taken together, these results demonstrate that fluorescently labeled HgTX(1) analogues comprise novel probes to characterize a subset of voltage-gated K+ channels.

Insertion of the full-length calcium channel alpha(1S) subunit into triads of skeletal muscle in vitro

A full-length and a C-terminally truncated form of the calcium channel alpha(1S) subunit can be isolated from skeletal muscle. Here we studied whether full-length alpha(1S) is functionally incorporated into the skeletal muscle excitation-contraction coupling apparatus. A fusion protein of alpha(1S) with the green fluorescent protein attached to its C-terminus (alpha(1S)-GFP) or alpha(1S) and GFP separately (alpha(1S)+GFP) were expressed in dysgenic myotubes, which lack endogenous alpha(1S). Full-length alpha(1S)-GFP was targeted into triad junctions and restored calcium currents and excitation-contraction coupling. GFP remained colocalized with alpha(1S), indicating that intact alpha(1S)-GFP was inserted into triads and that the C-terminus remained associated with the excitation-contraction coupling apparatus.

Current modulation and membrane targeting of the calcium channel alpha1C subunit are independent functions of the beta subunit

1. The beta subunits of voltage-sensitive calcium channels facilitate the incorporation of channels into the plasma membrane and modulate calcium currents. In order to determine whether these two effects of the beta subunit are interdependent or independent of each other we studied plasma membrane incorporation of the channel subunits with green fluorescent protein and immunofluorescence labelling, and current modulation with whole-cell and single-channel patch-clamp recordings in transiently transfected human embryonic kidney tsA201 cells. 2. Coexpression of rabbit cardiac muscle alpha1C with rabbit skeletal muscle beta1a, rabbit heart/brain beta2a or rat brain beta3 subunits resulted in the colocalization of alpha1C with beta and in a marked translocation of the channel complexes into the plasma membrane. In parallel, the whole-cell current density and single-channel open probability were increased. Furthermore, the beta2a isoform specifically altered the voltage dependence of current activation and the inactivation kinetics. 3. A single amino acid substitution in the beta subunit interaction domain of alpha1C (alpha1CY467S) disrupted the colocalization and plasma membrane targeting of both subunits without affecting the beta subunit-induced modulation of whole-cell currents and single-channel properties. 4. These results show that the modulation of calcium currents by beta subunits can be explained by beta subunit-induced changes of single-channel properties, but the formation of stable alpha1C-beta complexes and their increased incorporation into the plasma membrane appear not to be necessary for functional modulation.

Association of calcium channel alpha1S and beta1a subunits is required for the targeting of beta1a but not of alpha1S into skeletal muscle triads

The skeletal muscle L-type Ca2+ channel is a complex of five subunits that is specifically localized in the triad. Its primary function is the rapid activation of Ca2+ release from cytoplasmic stores in a process called excitation-contraction coupling. To study the role of alpha1S-beta1a interactions in the incorporation of the functional channel complex into the triad, alpha1S and beta1a [or a beta1a-green fluorescent protein (GFP) fusion protein] were expressed alone and in combination in myotubes of the dysgenic cell line GLT. betaGFP expressed in dysgenic myotubes that lack the skeletal muscle alpha1S subunit was diffusely distributed in the cytoplasm. On coexpression with the alpha1S subunit betaGFP distribution became clustered and colocalized with alpha1S immunofluorescence. Based on the colocalization of betaGFP and alpha1S with the ryanodine receptor the clusters were identified as T-tubule/sarcoplasmic reticulum junctions. Expression of alpha1S with and without beta1a restored Ca2+ currents and depolarization-induced Ca2+ release. The translocation of betaGFP from the cytoplasm into the junctions failed when betaGFP was coexpressed with alpha1S mutants in which the beta interaction domain had been altered (alpha1S-Y366S) or deleted (alpha1S-Delta351-380). Although alpha1S-Y366S did not associate with betaGFP it was incorporated into the junctions, and it restored Ca2+ currents and depolarization-induced Ca2+ release. Thus, beta1a requires the association with the beta interaction domain in the I-II cytoplasmic loop of alpha1S for its own incorporation into triad junctions, but stable alpha1S-beta1a association is not necessary for the targeting of alpha1S into the triads or for its normal function in Ca2+ conductance and excitation-contraction coupling.

Differential effects of Ca2+ channel beta1a and beta2a subunits on complex formation with alpha1S and on current expression in tsA201 cells

To study the interactions of the alpha1S subunit of the skeletal muscle L-type Ca2+ channel with the skeletal beta1a and the cardiac beta2a, these subunits were expressed alone or in combination in tsA201 cells. Immunofluorescence- and green fluorescent protein-labeling showed that, when expressed alone, beta1a was diffusely distributed throughout the cytoplasm, beta2a was localized in the plasma membrane, and alpha1S was concentrated in a tubular/reticular membrane system, presumably the endoplasmic reticulum (ER). Upon coexpression with alpha1S, beta1a became colocalized with alpha1S in the ER. Upon coexpression with beta2a, alpha1S redistributed to the plasma membrane, where it aggregated in large clusters. Coexpression of alpha1S with beta1a but not with beta2a increased the frequency at which cells expressed L-type currents. A point mutation (alpha1S-Y366S) or deletion (alpha1S-Delta351-380) in the beta interaction domain of alpha1S blocked both translocation of beta1a to the ER and beta2a-induced translocation of the alpha1S mutants to the plasma membrane. However, the point mutation did not interfere with beta1a-induced current stimulation. Thus, beta1a and beta2a are differentially distributed in tsA201 cells and upon coexpression with alpha1S, form alpha1S. beta complexes in different cellular compartments. Complex formation but not current stimulation requires the intact beta interaction domain in the I-II cytoplasmic loop of alpha1S.

A quantitative estimate of flash-induced Ca(2+)- and Na(+)-influx and Na+/Ca(2+)-exchange in blowfly Calliphora photoreceptors

The flash-induced Ca(2+)- and Na(+)-influx and Na+/Ca(2+)-exchange activity in blowfly Calliphora photoreceptors were investigated. The change in membrane potential, induced by a bright flash, was intracellularly measured in vivo. Based on a biophysical photoreceptor model, the Na(+)- and Ca(2+)-currents and concentration changes were determined from the first transient depolarization phase of the photoreceptor response. The activity of Na+/Ca(2+)-exchange was determined from the after depolarization phase. It appeared that the Na(+)-influx by Na+/Ca(2+)-exchange is about twice that through light-activated channels, suggesting a substantial contribution of Na+/Ca(2+)-exchange to Na(+)-regulation.