Coordination of the primary defense mechanisms against pathogens relies on the appropriate expression of pathogen recognition receptors (PRRs) triggering the early release of effector molecules of the innate immune system. To analyze the impact of this system on the counteraction of infections of the mammary gland (mastitis), we characterized the bovine gene encoding the key PRR Toll-like receptor 9 (TLR9) and mapped its precise position on chromosome BTA22. The sequence information was used to establish real-time PCR quantification assays to measure the mRNA abundances of TLR9, TLR2, and TLR4 together with those of β-defensin 5 (BNBD5), an early bactericidal effector molecule of the innate system, in healthy and infected mammary glands. Mastitis strongly increased (4- to 13-fold) the mRNA abundances of all of these genes except TLR9. Slight subclinical infections already caused a substantial increase in the copy numbers, though they did so the least for TLR9. Induction was not systemic, since mRNA abundance was low in uninfected control quarters of the udder but high in the severely infected quarters of the same animal. The number of TLR2 copies correlated well with those of TLR4, indicating coordinated regulation of these two PRRs during infection of the udder. Their coordinated regulation explains our unexpected observation that pureStaphylococcus aureusinfections caused a strong increase also in TLR4 mRNA abundance. In situ hybridizations revealed that BNBD5 is expressed predominantly in the mammary epithelial cells (MEC) of the infected gland. Our data therefore suggest a significant contribution of the innate immune system to counteract mastitis and attribute a prominent effector function to the MEC.

Siglecs (sialic acid-binding immunoglobulin-type lectins) are a family of immune regulatory receptors predominantly found on the cells of the hematopoietic system. A V-set Ig-like domain mediates the recognition of different sialylated glycoconjugates, which can lead to the activation or inhibition of the immune response, depending on the involved Siglecs. Siglecs are categorized into two subgroups: one including all CD33-related Siglecs and the other consisting of Siglec-1 (Sialoadhesin), Siglec-2 (CD22), Siglec-4 (myelin-associated glycoprotein, MAG) and Siglec-15. In contrast to the members of the CD33-related Siglecs, which share ∼50-99% sequence identity, Siglecs of the other subgroup show quite low homology (approximately 25-30% sequence identity). Based on the published sequences and functions of Siglecs, we performed phylogenetic analyses and sequence alignments to reveal the conservation of Siglecs throughout evolution. Therefore, we focused on the presence of Siglecs in different classes of vertebrates (fishes, amphibians, birds, reptiles and mammals), offering a bridge between the presence of different Siglecs and the biological situations of the selected animals.

The innate immune response involves a concerted network of induced gene products, preformed immune effectors, biochemical signalling cascades and specialised cells. However, the multifaceted activation of these defensive measures can derail or overshoot and, if left unchecked, overwhelm the host. A plenty of regulatory devices therefore mediate the fragile equilibrium between pathogen defence and pathophysiological manifestations. Over the past decade in particular, an almost complete set of teleostean sequences orthologous to mammalian immunoregulatory factors has been identified in various fish species, which prove the remarkable conservation of innate immune-control concepts among vertebrates. This review will present the current knowledge on more than 50 teleostean regulatory factors (plus additional fish-specific paralogs) that are of paramount importance for controlling the clotting cascade, the complement system, pattern-recognition pathways and cytokine-signalling networks. A special focus lies on those immunoregulatory features that have emerged as potential biomarker genes in transcriptome-wide research studies. Moreover, we report on the latest progress in elucidating control elements that act directly with immune-gene-encoding nucleic acids, such as transcription factors, hormone receptors and micro- and long noncoding RNAs. Investigations into the function of teleostean inhibitory factors are still mainly based on gene-expression profiling or overexpression studies. However, in support of structural and in-vitro analyses, evidence from in-vivo trials is also available and revealed many biochemical details on piscine immune regulation. The presence of multiple gene copies in fish adds a degree of complexity, as it is so far hardly understood if they might play distinct roles during inflammation. The present review addresses this and other open questions that should be tackled by fish immunologists in future.

A second-generation 5000 rad radiation hybrid (RH) map of the cattle genome was constructed primarily using cattle ESTs that were targeted to gaps in the existing cattle–human comparative map, as well as to sparsely populated map intervals. A total of 870 targeted markers were added, bringing the number of markers mapped on the RH₅₀₀₀ panel to 1913. Of these, 1463 have significant BLASTN hits (E < e^–5) against the human genome sequence. A cattle–human comparative map was created using human genome sequence coordinates of the paired orthologs. One-hundred and ninety-five conserved segments (defined by two or more genes) were identified between the cattle and human genomes, of which 31 are newly discovered and 34 were extended singletons on the first-generation map. The new map represents an improvement of 20% genome-wide comparative coverage compared with the first-generation map. Analysis of gene content within human genome regions where there are gaps in the comparative map revealed gaps with both significantly greater and significantly lower gene content. The new, more detailed cattle–human comparative map provides an improved resource for the analysis of mammalian chromosome evolution, the identification of candidate genes for economically important traits, and for proper alignment of sequence contigs on cattle chromosomes.

Several studies in a variety of breeds have reported at least two QTL for milk production traits, including milk fat synthesis on bovine chromosome 6 (BTA6), comprising a region that comparatively has been mapped to equivalent syntenic chromosome intervals in human, pig, and mouse harboring loci associated with type II diabetes and obesity-related traits. We identified the bovine peroxysome proliferator-activated receptor-γ coactivator-1α gene (PPARGC1A) as a plausible positional and functional candidate gene for a previously described QTL for milk fat yield on BTA6 because of its chromosomal position and its key role in energy, fat, and glucose metabolism. To analyze the role of the bovine PPARGC1A gene in regulation of milk fat synthesis in dairy cattle, we determined its cDNA sequence, genomic organization, chromosomal localization, and expression pattern. The bovine PPARGC1A gene is organized in 13 exons comprising 6,261 bp and is expressed at different levels in a large number of tissues. Bovine PPARGC1A cDNA and protein sequences showed substantial similarity (92–95%) to its respective orthologs from human, rat, and mouse. Screening for polymorphisms in the coding sequence, exon/intron boundaries, 5′- and 3′-untranslated regions, and promoter region of the PPARGC1A gene in sires with a different genotype at the QTL for milk fat yield as well as in a multibreed panel revealed a total of 11 polymorphic loci. A significant association between an SNP in intron 9 of the PPARGC1A gene and milk fat yield was observed in a major dairy cattle population, indicating that the PPARGC1A gene could be involved in genetic variation underlying the QTL for milk fat synthesis on BTA6.