The SUN Protein Mps3 Is Required for Spindle Pole Body Insertion into the Nuclear Membrane and Nuclear Envelope Homeostasis

The budding yeast spindle pole body (SPB) is anchored in the nuclear envelope so that it can simultaneously nucleate both nuclear and cytoplasmic microtubules. During SPB duplication, the newly formed SPB is inserted into the nuclear membrane. The mechanism of SPB insertion is poorly understood but likely involves the action of integral membrane proteins to mediate changes in the nuclear envelope itself, such as fusion of the inner and outer nuclear membranes. Analysis of the functional domains of the budding yeast SUN protein and SPB component Mps3 revealed that most regions are not essential for growth or SPB duplication under wild-type conditions. However, a novel dominant allele in the P-loop region, MPS3-G186K, displays defects in multiple steps in SPB duplication, including SPB insertion, indicating a previously unknown role for Mps3 in this step of SPB assembly. Characterization of the MPS3-G186K mutant by electron microscopy revealed severe over-proliferation of the inner nuclear membrane, which could be rescued by altering the characteristics of the nuclear envelope using both chemical and genetic methods. Lipid profiling revealed that cells lacking MPS3 contain abnormal amounts of certain types of polar and neutral lipids, and deletion or mutation of MPS3 can suppress growth defects associated with inhibition of sterol biosynthesis, suggesting that Mps3 directly affects lipid homeostasis. Therefore, we propose that Mps3 facilitates insertion of SPBs in the nuclear membrane by modulating nuclear envelope composition

Diagnosis of stress in the European eel

ICES/Special meeting on disease of commercially important marine fish and shellfish. No. 27 (1980)SIGLETIB Hannover: D.Dt.F./AC 1000 (14,78) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Pulmonary infections in swine induce altered porcine surfactant protein D expression and localization to dendritic cells in bronchial-associated lymphoid tissue

Surfactant protein D (SP-D) is a pattern-recognition molecule of the innate immune system that recognizes various microbial surface-specific carbohydrate and lipid patterns. In vitro data has suggested that this binding may lead to increased microbial association with macrophages and dendritic cells. The aim of the present in vivo study was to study the expression of porcine SP-D (pSP-D) in the lung during different pulmonary bacterial infections, and the effect of the routes of infection on this expression was elucidated. Furthermore, the aim was to study the in vivo spatial relationship among pSP-D, pathogens, phagocytic cells and dendritic cells. Lung tissue was collected from experimental and natural bronchopneumonias caused by Actinobacillus pleuropneumoniae or Staphylococcus aureus, and from embolic and diffuse interstitial pneumonia, caused by Staph. aureus or Arcanobacterium pyogenes and Streptococcus suis serotype 2, respectively. By comparing normal and diseased lung tissue from the same lungs, increased diffuse pSP-D immunoreactivity was seen in the surfactant in both acute and chronic bronchopneumonias, while such increased expression of pSP-D was generally not present in the interstitial pneumonias. Co-localization of pSP-D, alveolar macrophages and bacteria was demonstrated, and pSP-D showed a patchy distribution on the membranes of alveolar macrophages. SP-D immunoreactivity was intracellular in dendritic cells. The dendritic cells were identified by their morphology, the absence of macrophage marker immunoreactivity and the presence of dendritic cell marker immunoreactivity. Increased expression of pSP-D in the surfactant coincided with presence of pSP-D-positive dendritic cells in bronchus-associated lymphoid tissue (BALT), indicating a possible transport of pSP-D through the specialized M cells overlying (BALT). In conclusion, we have shown that pSP-D expression in the lung surfactant is induced by bacterial infection by an aerogenous route rather than by a haematogenous route, and that the protein interacts specifically with alveolar macrophages and with dendritic cells in microbial-induced BALT. The function of the interaction between pSP-D and dendritic cells in BALT remain unclear, but pSP-D could represent a link between the innate and adaptive immune system, facilitating the bacterial antigen presentation by dendritic cells in BALT