Congenital stationary night blindness (CSNB) is a non-progressive, clinically and genetically heterogeneous disease of impaired night vision. We report a naturally-occurring, stationary, autosomal recessive phenotype in beagle dogs with normal daylight vision but absent night vision. Affected dogs had normal retinas on clinical examination, but showed no detectable rod responses. They had “negative-type” mixed rod and cone responses in full-field ERGs. Their photopic long-flash ERGs had normal OFF-responses associated with severely reduced ON-responses. The phenotype is similar to the Schubert-Bornschein form of complete CSNB in humans. Homozygosity mapping ruled out most known CSNB candidates as well as CACNA2D4 and GNB3. Three remaining genes were excluded based on sequencing the open reading frame and intron-exon boundaries (RHO, NYX), causal to a different form of CSNB (RHO) or X-chromosome (NYX, CACNA1F) location. Among the genes expressed in the photoreceptors and their synaptic terminals, and mGluR6 cascade and modulators, reduced expression of GNAT1, CACNA2D4 and NYX was observed by qRT-PCR in both carrier (n = 2) and affected (n = 2) retinas whereas CACNA1F was down-regulated only in the affecteds. Retinal morphology revealed normal cellular layers and structure, and electron microscopy showed normal rod spherules and synaptic ribbons. No difference from normal was observed by immunohistochemistry (IHC) for antibodies labeling rods, cones and their presynaptic terminals. None of the retinas showed any sign of stress. Selected proteins of mGluR6 cascade and its modulators were examined by IHC and showed that PKCα weakly labeled the rod bipolar somata in the affected, but intensely labeled axonal terminals that appeared thickened and irregular. Dendritic terminals of ON-bipolar cells showed increased Goα labeling. Both PKCα and Goα labeled the more prominent bipolar dendrites that extended into the OPL in affected but not normal retinas. Interestingly, RGS11 showed no labeling in the affected retina. Our results indicate involvement of a yet unknown gene in this canine model of complete CSNB.

Sporothrix schenckii cells were grown on a medium containing yeast extract, neopeptone and glucose at 20 "C to obtain a mixture of mycelia and conidia, and at 35 "C to obtain yeast-like cells. The organism was maintained in the mycelial form, and its transformation to yeast at the higher temperature proceeded via conidia and 'intermediate cells' that then gave rise to yeast by a blastic mechanism. Cell-free extracts were analysed by PAGE at pH 8.0 and acid phosphatases (EC 3.1.3.2) were revealed by a sensitive detection reagent at pH 5.0. Mycelial, conidial and yeast extracts all had some acid phosphatase activity (M-I, C-I and Y-I) at the origin, although the proportion was highest for the yeast extracts. All of the bands that penetrated the gels had different electrophoretic mobilities. Mycelial and conidial extracts each had one other isoenzyme (M-I1 and C-11), while the yeast extracts had a total of five electrophoretically distinct acid phosphatases. Isoenzyme Y-I1 was further resolved into five closely related bands (Y-IIa to Y-He), the relative intensities of which varied with the phosphate nutrition of the yeast cells and the history of the extracts. The acid phosphatase isoenzymes were inhibited to various extents by sodium fluoride, L( +)-tartrate and phosphate, and showed interactions with citrate as opposed to acetate as the background buffer at pH 5.0.

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Suspensions of intact, yeast-like cells of Sporothrix schenckii exhibited an acid phosphatase (EC 3 . 1 .3.2) activity against pnitrophenyl phosphate of about 5 IU (g dry wt)-l, without recourse to membrane perturbation. This extra-cytoplasmic acid phosphatase was reversibly and competitively inhibited by orthophosphate (Ki = 2 mM at pH 5) but unaffected by L( +)-tartrate (in contradistinction to some of the cytoplasmic acid phosphatases of the same organism). Inactivation by NaF of the extra-cytoplasmic isoenzyme was irreversible and followed first order kinetics; sensitivity to NaF was decreased by the presence of citrate, phosphate or substrate. Neither K , (0.3 mM at pH 5) nor V,,, for this enzyme in acetate buffer was greatly affected by pH in the range 3-5 but the first order rate constant for inactivation by NaF was strongly dependent on pH (maximum at pH 3.5). Crude cell-free extracts of yeast cells had nine electrophoretically distinct acid phosphatase activity bands and, on the basis of the pattern of inhibitors, the extra-cytoplasmic activity was identified as Y-I, an isoenzyme that barely penetrates standard polyacrylamide gel electropherograms. Additional evidence for the assignment came from selective inactivation of this isoenzyme by short treatments of intact cells with NaF under conditions that did not allow penetration of the plasma membrane by the inhibitor and did not kill the cells.

Macrophages (M phi) and polymorphonuclear leukocytes (PMN) were obtained from C3H/He mice which had received intraperitoneal administration of an acidic fraction of bakers' yeast mannan (WAM025), 150 mg/kg/d, for 5d and the cells were investigated for their cell-injuring effect against MM46 tumor cells in vitro. The M phi displayed a marked cytolytic effect in the range of effector cells to target cells ratios of 100 to 200 with concomitant increase of lysosomal enzyme and active oxygen production. On the other hand, the PMN did not show the cytolytic effect, and the enhancing effect of the lysosomal enzyme activity was also very low, while these cells produced larger amounts of active oxygens and interleukin-1 (IL-1) than did the M phi.