The sequence of the major protein stored in ovine ceroid lipofuscinosis is identical with that of the dicyclohexylcarbodiimide-reactive proteolipid of mitochondrial ATP synthase.

The ceroid lipofuscinoses are a group of neurodegenerative lysosomal storage diseases of children and animals that are recessively inherited. In diseased individuals fluorescent storage bodies accumulate in a wide variety of cells, including neurons. Previous studies of these bodies isolated from tissues of affected sheep confirmed that the storage occurs in lysosomes, and showed that the storage body is mostly made of a single protein with an apparent molecular mass of 3500 Da with an N-terminal amino acid sequence that is the same as residues 1-40 of the c-subunit (or dicyclohexylcarbodi-imide-reactive proteolipid) of mitochondrial ATP synthase. In the present work we have shown by direct analysis that the stored protein is identical in sequence with the entire c-subunit of mitochondrial ATP synthase, a very hydrophobic protein of 75 amino acid residues. As far as can be detected by the Edman degradation, the stored protein appears not to have been subject to any post-translational modification other than the correct removal of the mitochondrial import sequences that have been shown in other experiments to be present at the N-terminal of its two different precursors. No other protein accumulates in the storage bodies to any significant extent. Taken with studies of the cDNAs for the c-subunit in normal and diseased sheep, these results indicate that the material that is stored in lysosomes of diseased animals has probably entered mitochondria and has been subjected to the proteolytic processing that is associated with mitochondrial import. This implies that the defect that leads to the lysosomal accumulation concerns the degradative pathway of the c-subunit of ATP synthase. An alternative, but less likely, hypothesis is that for some unknown reason the precursors of subunit c are being directly mis-targeted to lysosomes, where they become processed to yield a protein identical with the protein that is normally found in the mitochondrial ATP synthase assembly, and which then accumulates.     

Interactions ofCandida albicans with bacteria and salivary molecules in oral biofilms

The yeastCandida albicans coaggregates with a variety of streptococcal species, an interaction that may promote oral colonization by yeast cells.C. albicans andCandida tropicalis are the yeasts most frequently isolated from the human oral cavity and our data demonstrate that both these species bind toStreptococcus gordonii NCTC 7869 while two otherCandida species (Candida krusei andCandida kefyr) do not. Adherence ofC. albicans was greatest when the yeast had been grown at 30° C to mid-exponential growth phase. For 21 strains ofC. albicans there was a positive correlation between the ability to adhere toS. gordonii and adherence to experimental salivary pellicle. Whole saliva either stimulated or slightly inhibited adherence ofC. albicans toS. gordonii depending on the streptococcal growth conditions. The results suggest that the major salivary adhesins and coaggregation adhesins ofC. albicans are co-expressed.     

Uptake of saline groundwater by plants: An analytical model for semi-arid and arid areas

An analytical model, based on unsaturated zone water and solute balances, was developed to describe the uptake of saline groundwater by plants in dry regions. It was assumed that: i. initially, the profile had low water and salt contents to some depth; ii. both water and solutes move upwards from the water table by piston flow due only to plant water extraction; iii. the uptake of water concentrates solutes in the soil solution until some threshold salinity is reached, above which plants can no longer extract water due to osmotic effects; iv. uptake of the groundwater does not affect the water table level; and v. uptake of groundwater is only limited by transmission of groundwater through the soil. Model predictions were compared with measurements of groundwater uptake made over 15 months at five sites in aEucalyptus forest in a semi-arid area, using independently measured model parameters. Depth and salinity of groundwater, and soil type varied greatly between sites. Predicted groundwater uptake rates were close to measured values, generally being within ∼ 0.1 mm day^-1. Sensitivity analysis showed that groundwater depth and salinity were the main controls on uptake of groundwater, while soil properties appeared to have a lesser effect. The model showed that uptake of groundwater would result in complete salinisation of the soil profile within 4 to 30 yr at the sites studied, unless salts were leached from the soil by rainfall or flood waters. However, a relatively small amount of annual leaching may be sufficient to allow groundwater uptake to continue. Thus groundwaters, even when saline, may be important sources of water to plants in arid and semi-arid areas.     

Characterization of humoral and CD4+ cellular responses after genetic immunization with retroviral vectors expressing different forms of the hepatitis B virus core and e antigens.

The humoral and CD4+ cellular immune responses in mice following genetic immunization with three retroviral vectors encoding different forms of hepatitis B virus core antigen (HBcAg) and e antigen (HBeAg) were analyzed. The retroviral vectors induced expression of intracellular HBcAg (HBc[3A4]), secreted HBeAg (HBe[5A2]), or an intracellular HBcAg-neomycin phosphoryltransferase fusion protein (HBc-NEO[6A3]). Specific antibody levels and immunoglobulin G isotype restriction were highly dependent on both the host major histocompatibility complex and the transferred gene. Humoral and CD4+ cellular HBcAg and/or HBeAg (HBc/eAg)-specific immune responses following retroviral vector immunization were of a lower magnitude but followed the same characteristics compared with those after immunization with HBc/eAg in adjuvant. Two factors influenced the humoral responses. First, in vivo depletion of CD8+ cells in HBc-NEO[6A3]-immunized H-2k mice abrogated both HBcAg-specific antibodies and in vitro-detectable cytotoxic T lymphocytes. Second, priming of H-2b mice with an HBc/eAg-derived T-helper (Th) peptide in adjuvant prior to retroviral vector immunization greatly enhanced the HBc/eAg-specific humoral responses to all three vectors, suggesting that insufficient HBc/eAg-specific CD4+ Th-cell priming limits the humoral responses. In conclusion, direct injection of retroviral vectors seems to be effective in priming HBc/eAg-specific CD8+ but comparatively inefficient in priming CD4+ Th cells and subsequently specific antibodies. However, the limited HBc/eAg-specific CD4+ cell priming can effectively be circumvented by prior administration of a recombinant or synthetic form of HBc/eAg in adjuvant.     

The intrauterine contraceptive device.

This presentation brings into perspective the most recent information on intrauterine contraceptive devices. A comprehensive review of the literature is presented in a manner meaningful to the clinician. The advantages and disadvantages of this method of contraception, the problems that arise and the recommended methods of management are discussed. An updated review of the literature with regard to bleeding, pain, expulsion of the device, infection, uterine perforation and pregnancy is also presented.     

Hepatocystis Parasitemia in Wild Kenya Vervet Monkeys (Cercopithecus aethiops)

Blood smears of 159 vervet monkeys from three sites in Kenya were stained with Giemsa and examined for Hepatocystis parasites. The populations differ in incidence of parasitemia, ranging from 0–62% affected individuals. These differences are probably due to altitude and local environmental conditions.     

Isolation and characterization of adult rat hearts cells.

Adult rat heart muscle cells were isolated after simultaneous perfusion of multiple (two to eight) hearts with buffered salt solutions containing collagenase and hyaluronidase. Yields (35 to 50% of ventricular weight with approximately 70% viability) are quantitatively suitable for metabolic studies. Viability has been determined by the ability of intact cells to exclude trypan blue and the inability of intact cells to oxidize exogenous succinate. Micrographs show that the fine structure of the isolated cells is well ordered. Cell concentrations of glycogen, glucose 6-phosphate, citrate, and various enzymes were similar to those of intact heart. ATP and creatine phosphate concentrations were lower than in whole hearts. Adenosine 3′,5′-monophosphate concentrations were somewhat elevated. Deoxyribonucleic acid was lower than in whole tissue. The isolated cells retain certain metabolic control mechanisms. The uncoupler of oxidative phosphorylation, 2,4-dinitrophenol, increased oxygen consumption severalfold, whereas exogenous ADP had no effect on respiration. Under anaerobic conditions the rates of glucose utilization and lactate production were faster than in the presence of oxygen, indicating retention of the Pasteur effect. The addition of glucose and insulin caused a decrease in oxygen uptake or the Crabtree effect. Exogenously added pyruvate decreased glycolytic flux and produced a pronounced increase in intracellular citrate and glucose 6-phosphate. Isoproterenol stimulated adenylate cyclase activity of the isolated cells at the same concentrations effective with intact heart preparations. Isoproterenol and glucagon caused the activation of phosphorylase. The cells deteriorated as a function of incubation time, as indicated by a decrease in ATP content and a loss of lactate dehydrogenase into the medium. Cell deterioration was greatly accelerated by Ca²⁺ at concentrations greater than 10^?5m.