A Sperm Midpiece Defect in a Hereford Bull with Variable Semen Quality and Freezability

A midpiece sperm defect with a frequency of 25-35% in ejaculates obtained from a Hereford bull with a 60 d non-retum rate of 76.4% after careful pre- and postfreeze semen selection was studied in light microscope and by transmission electron microscopy. The defect consisted in a folding and coiling of the distal midpiece characterized by disorganization and irregularity of mitochondria surrounding the axial fiber bundle, combined with retraction of doublet fibers and dislocation and fracturing of these elements and the corresponding dense fibers. Based on examination of the sper- matogenic epithelium it was concluded that the alterations in the axial fiber bundle were secondary to those in the mitochondrial sheath. The abnormality appeared to be related to the “Dag-like” defect earlier observed in different breeds.     

Double blind randomised controlled trial of effect of metoprolol on myocardial ischaemia during endoscopic cholangiopancreatography.

OBJECTIVE--To evaluate the effect of metoprolol, a beta adrenergic blocking drug, on the occurrence of myocardial ischaemia during endoscopic cholangiopancreatography. DESIGN--Double blind, randomised, controlled trial. SETTING--University Hospital. SUBJECTS--38 (two groups of 19) patients scheduled for endoscopic cholangiopancreatography. INTERVENTIONS--Metoprolol 100 mg or placebo as premedication two hours before endoscopy. MAIN OUTCOME MEASURES--Heart rate, arterial oxygen saturation by continuous pulse oximetry, ST segment changes during endoscopic cholangiopancreatography (an ST segment deviation > 1 mV was defined as myocardial ischaemia), electrocardiogram monitored continuously with a Holter tape recorder. RESULTS--All patients had increased heart rate during endoscopy compared with rate before endoscopy, but heart rate during endoscopy was significantly lower in the metoprolol group compared with the placebo group (P = 0.0002). Twenty one patients (16 placebo, 5 metoprolol; P = 0.0008) developed tachycardia (heart rate > 100/min) during the procedure, and 11 patients (10 placebo, 1 metoprolol; P = 0.003) developed myocardial ischaemia. One patient in the placebo group had an acute inferolateral myocardial infarction. In the 10 other patients with signs of myocardial ischaemia during endoscopy the ST deviation disappeared when the endoscope was retracted. In all patients myocardial ischaemia was related to increases in heart rate, and 10 of the 11 patients had tachycardia coherent with myocardial ischaemia. CONCLUSIONS--Metoprolol prevented myocardial ischaemia during endoscopic cholangiopancreatography, probably through lowering the heart rate. Thus, tachycardia seems to be a key pathogenic factor in the development of myocardial ischaemia during endoscopy.     

Identification of a locus involved in meningococcal lipopolysaccharide biosynthesis by deletion mutagenesis

A novel method for insertion/deletion mutagenesis in meningococci was devised. This consisted of ligating a digest of total chromosomal DNA to a 1.1 kb restriction fragment containing an erythromycin-resistance marker ( ermC ), and subsequent transformation of the ligation mixture into the homologous meningococcal strain H44/76. Southern blotting of a number of the resulting erythromycin-resistant transformants demonstrated that all carried the ermC gene inserted at different positions in the chromosome. Mutants with a specific phenotype were identified by screening with the anti-lipopolysaccharide (LPS) monoclonal antibody MN4A8B2, which is specific for immunotype L3. In this way, two independent L3-negative mutant strains were isolated. In transformation experiments with chromosomal DNA from these mutants, erythromycin-resistance and lack of MN4A8B2 reactivity were always linked, showing that the insertion/deletion was in a locus involved in LPS biosynthesis. On SDS–PAGE, the mutant LPS displayed an electrophoretic mobility intermediate between that produced by the previously isolated galE and rfaF mutant strains. Chemical analysis of the mutant LPS revealed that the structure was probably lipid A–(KDO)₂–(Hep)₂. Chromosomal DNA flanking the ermC insertion in these two mutant strains was cloned, and used as probe for the isolation of the corresponding region of the wild-type strain. From hybridization and polymerase chain reaction (PCR) analysis, it could be concluded that both mutations map to the same locus. The affected gene probably encodes the glycosyltransferase necessary for adding N -acetylglucosamine to heptose.     

Direct effects of vitamin D3 analogues on G-protein mediated signalling systems in rat osteosarcoma cells and rat pituitary adenoma cells

In normal rats treated with 1,25(OH)₂D₃ or 24,25(OH)₂D₃, serum Ca²⁺, ALP, PRL and GH are significantly altered. In order to study the primary effect of vitamin D₃ analogues on target organ function, rat UMR 106 osteosarcoma and GH₃ pituitary adenoma cells in monolayer culture were exposed accordingly.Surprisingly, prolonged exposure of these cell lines to physiological levels of either 1,25(OH)₂D₃ or 24,25(OH)₂D₃ did not significantly affect the secretory parameters (ALP, PRL or GH) tested. However, 1,25(OH)₂D₃ exposure significantly reduced PTH- and Gpp(NH)p-elicited AC as well as Gpp(NH)p-stimulated PLC activities in the UMR 106 cells. These changes were accompanied by an increase and decrease in the membrane contents of the G-protein subunits G₃₆ and G_q/11, respectively. In contrast, 24,25(OH)₂D₃ remained without significant biological effect on these signalling systems despite concomitantly augmented levels of G₃₆. TRH- and Gpp(NH)p-elicited PLC activities in the GH₃ cells were significantly reduced by 1,25(OH)₂D₃ with a concurrent reduction in cellular amounts of G_q/11, however, 24,25(OH)₂D₃ did not significantly alter any signalling systems nor G-proteins analyzed.It is concluded that the osteoblastic and pituitary cell secretion of ALP, PRL and GH remain unaffected by the presence of 1,25(OH)₂D₃ and 24,25(OH)₂D₃, despite distinct alterations in components of G-protein mediated signalling pathways. Hence, other factors like ambient Ca²⁺ may be responsible for the perturbed secretory patterns of ALP and PRL seen in vitamin D₃ treated rats.Abbreviations AC adenylate cyclase - ALP alkaline phosphatase - BGP osteocalcin - BSA bovine serum albumin - DA dopamine - DAG diacylglycerol - GH growth hormone - GHRH growth hormone releasing hormone - Gpp(NH)p guanosine 5-[-imido]triphosphate - G-protein guanine nucleotide-binding regulatory protein - G_s etc. G_s protein -subunit - IP₃ inositol 1,4,5 trisphosphate - OAF osteoclast activating factor - PGE₂ prostaglandin E₂ - PKA & PKC protein kinase A & C - PLC phospholipase C - PRL prolactin - PTH parathyroid hormone - SRIF somatostatin - TRH thyrotropin releasing hormone - VIP vasoactive intestinal peptide - 25(OH)D₃ 25 hydroxy vitamin D₃ - 1,25(OH)₂D₃ 1·25 dihydroxy vitamin D₃ - 24,25(OH)₂D₃ 24,25 dihydroxy vitamin D₃     

Succession and soil development in man-made coastal ecosystems at the Baltic Sea

By the creation of Køge Bay Seaside Park in 1978 the opportunity was given to study the establishment of vegetation and primary succession in a man-made coastal area. As the soil consists of marine material from the Baltic Sea, no organic matter or seedbank was present. The first steps of primary succession were followed in 1980, when the initial inventories of flora immigration and soil development were carried out in coastal grasslands and plantings. The surveys were repeated in 1992 and 1993. Except for the planted woody species and a few sown grasses, all other species of plants have reached the area through natural dispersal of diaspores. The total number of species in the permanent plots has increased from 26 in 1980 to 91 in 1993. The results indicate that this number will continue to increase in the coming years until a certain level. Then it will probably decrease as a result of competition from woody species, unless the vegetation is kept in a steady state by disturbances or management. Today the area is very far from the initial situation, and the off-shore barrier has changed towards a landscape dominated by small groves and grasslands of an urban common type.     

Uracil uptake in Escherichia coli K-12: isolation of uraA mutants and cloning of the gene.

Mutants defective in utilization of uracil at low concentrations have been isolated and characterized. The mutations in question (uraA) map close to the upp gene encoding uracil phosphoribosyltransferase. By complementation analysis, a plasmid that complements the uraA mutation has been isolated. The uraA gene was shown to be the second gene in a bicistronic operon with upp as the promoter proximal gene. The nucleotide sequence of the gene was determined, and the gene encodes a hydrophobic membrane protein with a calculated Mr of 45,030. The UraA protein has been identified in sodium dodecyl sulfate-polyacrylamide gels in the membrane fraction of minicells harboring the uraA plasmids.     

PHYLOGENETIC AFFINITIES OF THE SARCINOCHRYSIDALES AND CHRYSOMERIDALES (HETEROKONTA) BASED ON ANALYSES OF MOLECULAR AND COMBINED DATA1

Small-subunit ribosomal RNA nucleotide sequences were inferred for Giraudyopsis stellifera Dangeard (Chrysomeridales), as well as for Pulvinaria sp. and Sarcinochrysis marina Geitler (Sarcinochrysidales,). Phylogenetic analyses of the molecular data indicate that the former is weakly related to the Phaeophyceae/Xanthophyceae clade, whereas the latter two have affinities to the Pelagophyceae, and the Sarcinochrysidales sensu stricto is transferred to this class. A recent study proposed that the Pelagophyceae belongs to a larger assemblage of chromophytic species characterized by reduced flagellar apparatuses. Although the flagellar apparatus characterizing the Sarcinochrysidales is reduced relative to the Chysomeridaels and some other chromophytes, it is the most complicated to be associated with “the reduced flagellar apparatus” lineage. Cladistic analyses of a traditional data set (largely ultrastructural features of the flagellar apparatus) and a combined traditional/molecular data set were used to assess the evolutionary trends of reduction in the flagellar apparatus within the heterokont chromophytes.     

Taxonomy ofPenicillium nalgiovense isolates from mould-fermented sausages

A large number ofPenicillium nalgiovense isolates from mould fermented sausages and the ex type culture were examined for characters of morphology, physiology and production of secondary metabolites. To separate biotypes within theP. nalgiovense species, the data obtained were evaluated using multivariate statistical methods. The macromorphological characters of the ex type culture and isolates from meat products appeared to be distinctive. The ex type culture is characterized by a brown reverse on both Czapek yeast extract and malt extract agar while the isolates from meat products have a yellow to orange reverse. Proteolytic and/or lipolytic activity was demonstrated by 75% of the examined cultures and all of them demonstrated ability to utilize lactate as sole carbon source. Growth on creatine sucrose agar was very inhibited and acid production was absent or very weak. TLC analysis showed production of three unknown secondary metabolites that constituted the characteristic profile. HPLC analysis showed production of only three known secondary metabolites; chrysogine (96%), nalgiolaxin and nalgiovensin (9%). The ex type culture produced nalgiolaxin and nalgiovensin but not chrysogine. The chemometric evaluation showed thatP. nalgiovense isolates from meat products from a homogenous species, which can not be divided into biotypes. The only indication of grouping, beside a separation of the ex type culture, was related to the conidium colour (white, turquoise or grey green). The examinedP. nalgiovense isolates showed some resemblance (morphologically and chemically) toP. chrysogenum.     

A family of modular type mannuronan C-5-epimerase genes controls alginate structure in Azotobacter vinelandii

The ToxR protein is a transmembrane protein that regulates the expression of several virulence factors of Vibrio cholerae. Previous analysis of fusion proteins between ToxR and alkaline phosphatase (ToxR-PhoA) suggested that ToxR was active as a dimer. In order to determine whether dimerization of the ToxR periplasmic domain was essential for activity, this domain was replaced by monomeric and dimeric protein domains. Surprisingly, PhoA (dimeric), β-lactamase (monomeric, ToxR–Bla), or the leucine zipper of GCN4 (dimeric, ToxR-GCN4-M) could substitute functionally for the ToxR periplasmic domain. ToxR-GCN4 fusion proteins, in which the ToxR trans-membrane domain was eliminated (ToxR-GCN4-C), were inactive, but an additional fusion protein that contained a heterologous membrane-spanning domain retained activity. Strains containing each of these ToxR fusion proteins were analysed for in vivo colonization properties and response to in vitro growth conditions that are known to affect expression of the ToxR regulon. Strains containing ToxR-GCN4-M and ToxR-Bla responded like wild-type strains to in vitro growth conditions. In the infant-mouse colonization model, strains containing ToxR fusion proteins were all deficient in colonization relative to strains containing wild-type ToxR, and strains containing monomeric ToxR-Bla were most severely outcompeted. These results suggest that, under in vitro conditions, ToxR does not require a dimerized periplasmic domain, but that, under in vivo conditions, the correct conformation of the ToxR periplasmic domain may be more important for function.