Isoforms of Na,K-ATPase inArtemia salina: II. Tissue distribution and kinetic characterization

Summary To characterize the molecular properties conveyed by the isoforms of the subunit of Na,K-ATPase, the two major transepithelial transporting organs in the brine shrimp (Artemia salina), the salt glands and intestines, were isolated in pure form. The isoforms were quantified by ATP-sensitive fluorescein isothiocyanate (FITC) labeling. The salt gland enzyme exhibits only the 1 isoform, whereas the intestinal enzyme exhibits both the 1 and the 2 isoforms. After 32 hours of development, Na,K-ATPase activity [in mol P_i/mg protein/hr (1u)] in whole homogenates was 32±6 in the salt glands and 12±3 in the intestinal preparations (mean±sem). The apparent half-maximal activation constants (K _1/2) of the salt gland enzyme as compared to the intestinal enzyme were 3.7±0.6mm vs. 23.5±4mm (P<0.01) for Na⁺, 16.6±2.2mm vs. 8.29±1.5mm for K⁺ (P<0.01), and 0.87±0.8mm vs. 0.79±1.1mm for ATP (NS). The apparentK _i's for ouabain inhibition were 1.1×10^–4 m vs. 2×10^–5 m, respectively. Treatment of whole homogenates with deoxycholic acid (DOC) produced a maximal Na,K-ATPase activation of 46% in the salt gland as compared to 23% in the intestinal enzyme. Similar differences were found with sodium dodecyl sulfate (SDS). The two distinct forms of Na,K-ATPase isolated from the brine shrimp differed markedly in three kinetic parameters as well as in detergent sensitivity. The differences inK _1/2 for Na⁺ and K⁺ are more marked than those reported for the mammalian Na,K-ATPase isoforms. These differences may be attributed to the relative abundances of the subunit isoforms; other potential determinants (e.g. differences in membrane lipids), however, have not been investigated.During the tenure of an Educational Commission For Foreign Medical Graduates Visiting Associate Professorship.     

MORBILLIVIRUS INFECTION IN BOTTLENOSE DOLPHINS: EVIDENCE FOR RECURRENT EPIZOOTICS IN THE WESTERN ATLANTIC AND GULF OF MEXICO

Morbillivirus infection is widespread among odontocetes of the western Atlantic and Gulf of Mexico. Serologic evidence of infection in bottlenose dolphins, Tursiops truncatus , was first detected during an epizootic along the mid-Atlantic coast in 1987. Here, we report recurrent epizootics in the coastal dolphin population since at least the early 1980s based on serological surveys and regional stranding frequencies. The first observed epizootic of this series occurred in the Indian and Banana Rivers in 1982 and was followed by others on the mid-Atlantic coast in 1987–1988 and in the Gulf of Mexico between 1992 and 1994. This temporal pattern of infection is likely facilitated by the population size and its fragmentation into relatively discrete coastal communities. Introduction of morbillivirus into a community with a sufficient number of naive hosts may precipitate an epizootic, depending on the potential for transmission within the group. Propagation of an epizootic along the coast is probably determined by frequency of contact between adjacent communities and seasonal migrations.
Morbillivirus antibodies were also detected in serum from offshore bottlenose dolphins. The sero-prevalence in the latter may be higher than in coastal dolphins because of their close association with enzootically infected pilot whales ( Globicephala spp.). Occasional contact between offshore and coastal dolphins may provide an epizootiologic link between pilot whales and coastal dolphin communities.     

Molecular characterization of three Mhc class II B haplotypes in the ring-necked pheasant

We investigated the class II B genes in free-ranging population of the ring-necked pheasant Phasianus colchicus by a combination of restriction fragment length polymorphism (RFLP), polymerase chain reaction (PCR), and DNA sequencing. Special attention was paid to the variation in the second exon, which encodes the peptide-binding ₁-domain. The population was introduced, but it still exhibited major histocompatibility complex polymorphism with at least three segregating class II B haplotypes and consequently six genotypes. We found two class II B genes associated with each haplotype. The class II B genes of birds had until then only been molecularly characterized in the domestic chicken. the pheasant genes were highly variable, although one of the amplified sequences was found in two different haplotypes. Taken together, the most polymorphic positions (residues 37 and 38) were not identical in any of the predicted protein sequences, but all except one of the motifs had already been foud in the domestic chicken. Structurally important features in mammalian class II B genes were generally conserved also in the pheasant sequences, but the loss of a potential salt bridge constituent (Arg₇₂) in several sequences may suggest a slightly different structure of the adjacent parts of the peptide-binding groove. The pheasant genes are most closely related to the so called B-LBII family in the chicken, indicating that this represents a major line of development among avian class II B genes.The nucleotide sequence data reported in this paper have been submitted to the EMBL nucleotide sequence database and have been assigned the accession numbers X75403-X75407. Correspondence to: H. Wittzell, Department of Theoretical Ecology, Ecology Building, Lund University, S-223 62 Lund, Sweden.     

Antigenic determinants of measles virus hemagglutinin associated with neurovirulence.

The biological activity of monoclonal antibodies specific for the hemagglutinin protein of measles virus strain CAM recognizing six epitope groups according to their binding properties to measles virus strain CAM/R401 was investigated in vivo in our rat model of measles encephalitis. When injected intraperitoneally into measles virus-infected suckling rats, some monoclonal antibodies modified the disease process and prevented the necrotizing encephalopathy seen in untreated animals. The analysis of measles virus brain isolates revealed emergence of variants that resisted neutralization with the passively transferred selecting monoclonal antibody but not with other monoclonal antibodies. Monoclonal antibody escape mutants were also isolated in vitro, and their neurovirulence varied in the animal model. Sequence data from the hemagglutinin gene of measles virus localize a major antigenic surface determinant of the hemagglutinin protein between amino acid residues 368 and 396, which may be functionally important for neurovirulence. The data indicate that the interaction of antibodies with the measles virus H protein plays an important role in the selection of neurovirulent variants. These variants have biological properties different from those of the parent CAM virus.     

Metabolism of pyrimidine bases and nucleosides in Bacillus subtilis.

In Bacillus subtilis, uracil (Ura), uridine (Urd), and deoxyuridine (dUrd) are metabolized through pathways similar to those of enteric bacteria. Ura is probably converted to uridine 5'-monophosphate by uridine 5'-monophosphate pyrophosphorylase. More than 95% of dUrd added to cultures is converted to Ura and deoxyribose-1-phosphate. Although dUrd kinase activity is detectable in vitro, this enzyme does not seem to play an important role in the metabolism of dUrd. The metabolism of cytosine (Cyt), cytidine (Cyd), and deoxycytidine (dCyd) in B. subtilis appears to be different from that in enteric bacteria. Cytosine cannot be used by Ura-requiring mutants as pyrimidine source. dCyd is deaminated by dCyd-Cyd deaminase or phosphorylated to dCyd nucleotides by dCyd kinase. Cyd is deaminated by dCyd-Cyd deaminase of phosphorylated by Cyd kinase. This Cyd kinase activity has never been reported for B. subtilis.     

Deoxyribonucleoside-requiring mutants of Bacillus subtilis.

A number of deoxyribonucleoside-requiring mutants (dns) of Bacillus subtilis were isolated and their growth characteristics and ribonucleotide reductase activities were compared with those of the wild type and of a dna mutant (tsA13). Both tsA13 and dns mutants required the presence of a mixture of deoxyribonucleosides for growth at 45 degrees C but not at 25 degrees C. All the mutant strains tested contained ribonucleotide reductase activity which showed heat sensitivity similar to that of the enzyme from a wild-type strain. The reductase in B. subtilis seemed to reduce ribonucleoside triphosphates in a similar manner to the enzyme in Lactobacillus leichmannii.     

Alternative complement pathway-dependent ingestion of fluolite particles by human granulocytes

Fluorescent particles (Fluolite) with an average size of 0.1 micrometers were ingested by human granulocytes after incubation in fresh normal human serum (NHS). Ingestion was assessed by visual counting in a fluorescent microscope of cells containing particles. Ingestion required fresh normal serum and did not occur when serum was heated for 30 min at 50 degrees C or in the presence of ethylenediaminetetraacetic acid (EDTA). It did not occur in serum genetically deficient in C3b inactivator or in C3. Phagocytic activity was restored to C3-deficient serum by purified human C3 and to heat inactivated serum by purified factor B. Opsonic activity was present in NHS containing 5 mM Mg++ and 10 mM ethyleneglycoltetraacetic acid (EGTA) and in human serum genetically deficient in human C components C2 and C5. Agammaglobulinemic sera had normal opsonic activity. Opsonization of particles in this system is mediated through the alternative pathway of C activation, and its measurement serves as a simple quantitative functional assay for this system.     

Comparative cradle to grave environmental life cycle assessment of traditional and extensive vegetative roofs: an application for the Lebanese context

The International Journal of Life Cycle Assessment - Vegetative roofs (VRs) are fully planted roof spaces that offer aesthetic view, storm water management, sound insulation, energy savings, and...     

Correction to: Sex and race differences of cerebrospinal fluid metabolites in healthy individuals

Metabolomics - Metabolomics applications to the aquaculture research are increasing steadily. The use of standardized proton nuclear magnetic resonance (1H NMR) spectroscopy can provide the...     

Lipidomics Reveals Early Metabolic Changes in Subjects with Schizophrenia: Effects of Atypical Antipsychotics

There is a critical need for mapping early metabolic changes in schizophrenia to capture failures in regulation of biochemical pathways and networks. This information could provide valuable insights about disease mechanisms, trajectory of disease progression, and diagnostic biomarkers. We used a lipidomics platform to measure individual lipid species in 20 drug-naïve patients with a first episode of schizophrenia (FE group), 20 patients with chronic schizophrenia that had not adhered to prescribed medications (RE group), and 29 race-matched control subjects without schizophrenia. Lipid metabolic profiles were evaluated and compared between study groups and within groups before and after treatment with atypical antipsychotics, risperidone and aripiprazole. Finally, we mapped lipid profiles to n3 and n6 fatty acid synthesis pathways to elucidate which enzymes might be affected by disease and treatment. Compared to controls, the FE group showed significant down-regulation of several n3 polyunsaturated fatty acids (PUFAs), including 20:5n3, 22:5n3, and 22:6n3 within the phosphatidylcholine and phosphatidylethanolamine lipid classes. Differences between FE and controls were only observed in the n3 class PUFAs; no differences where noted in n6 class PUFAs. The RE group was not significantly different from controls, although some compositional differences within PUFAs were noted. Drug treatment was able to correct the aberrant PUFA levels noted in FE patients, but changes in re patients were not corrective. Treatment caused increases in both n3 and n6 class lipids. These results supported the hypothesis that phospholipid n3 fatty acid deficits are present early in the course of schizophrenia and tend not to persist throughout its course. These changes in lipid metabolism could indicate a metabolic vulnerability in patients with schizophrenia that occurs early in development of the disease.