Evidence for Linkage of Bipolar Disorder to Chromosome 18 with a Parent-of-Origin Effect

A susceptibility gene on chromosome 18 and a parent-of-origin effect have been suggested for bipolar affective disorder (BPAD). We have studied 28 nuclear families selected for apparent unilineal transmission of the BPAD phenotype, by using 31 polymorphic markers spanning chromosome 18. Evidence for linkage was tested with affected-sib-pair and LOD score methods under two definitions of the affected phenotype. The affected-sib-pair analyses indicated excess allele sharing for markers on 18p within the region reported previously. The greatest sharing was at D18S37: 64% in bipolar and recurrent unipolar (RUP) sib pairs (P = .0006). In addition, excess sharing of the paternally, but not maternally, transmitted alleles was observed at three markers on 18q: at D18S41, 51 bipolar and RUP sib pairs were concordant for paternally transmitted alleles, and 21 pairs were discordant (P = .0004). The evidence for linkage to loci on both 18p and 18q was strongest in the 11 paternal pedigrees, i.e., those in which the father or one of the father's sibs is affected. In these pedigrees, the greatest allele sharing (81%; P = .00002) and the highest LOD score (3.51; θ = 0.0) were observed at D18S41. Our results provide further support for linkage of BPAD to chromosome 18 and the first molecular evidence for a parent-of-origin effect operating in this disorder. The number of loci involved, and their precise location, require further study.     

A common gene for juvenile and adult-onset primary open-angle glaucomas confined on chromosome 1q.

Primary open-angle glaucoma (POAG), which causes progressive loss of the visual fields, was subdivided into two groups according to age at onset: (1) chronic open-angle glaucoma (COAG) diagnosed after age 40 years and (2) juvenile open-angle glaucoma (JOAG) diagnosed between 3 years of age and early adulthood. A JOAG gene (GLC1A) was recently mapped to chromosome 1q. We studied 142 members of a huge multigenerational French Canadian family affected with autosomal dominant POAG. Either JOAG or COAG was diagnosed in 40 patients. Six subjects were also diagnosed with ocular hypertension (OHT), which may lead to POAG. To localize a common disease gene that might be responsible for both glaucoma subsets, we performed linkage analysis considering JOAG and COAG under the same phenotypic category. JOAG/COAG was tightly linked to seven microsatellite markers on chromosome 1q23-q25; a maximum lod score of 6.62 was obtained with AF-M278ye5. To refine the disease locus, we exploited a recombination mapping strategy based on a unique founder effect. The same characteristic haplotype, composed of 14 markers spanning 12 cM between loci D1S196 and D1S212, was recognized in all persons affected by JOAG, COAG, or OHT, but it did not occur in unaffected spouses and in normal family members > 35 years of age, except for three obligatory carriers. Key recombination events confined the disease region within a 9-cM interval between loci D1S445 and D1S416/D1S480. These observations demonstrate that the GLC1A gene is responsible for both adult-onset and juvenile glaucomas and suggest that the JOAG and COAG categories within this family may be part of a clinical continuum artificially divided at age 40 years.     

Immobilization of tyrosinase for use in nonaqueous media: Enzyme deactivation phenomena

Summary We have investigated features for minimizing the inactivation of tyrosinase (E.C. 1.14.18.1) that is caused by immobilization on glass beads and Celite^®. The degree of inactivation is dependent on the enzyme loading and the carrier's surface area. Addition of a sacrificial protein during the immobilization procedure offers a protective effect with increased residual activity on the basis of comparable enzyme loading.     

Rapid Determination of Conidial Viability for Entomopathogenic Hyphomycetes Using Fluorescence Microscopy Techniques

The viability of conidia from two species of deuteromycetes fungi pathogenic to insects was determined using two fluorochrome stains, fluorescein diacetate (FDA) and propidium iodide (PI). These stains were used either alone or in combination, and results were compared with standard conidial germination tests. FDA fluoresces bright green in viable conidia and PI fluoresces red in non-viable conidia, when viewed using specific fluorescence microscopic techniques. Conidia from two isolates of Paecilomyces fumosoroseus (Wize) Brown and Smith and two isolates of Beauveria bassiana (Balsamo) Vuillemin were evaluated. Conidia were suspended in deionized water and half of each suspension was treated with microwave radiation to kill all the conidia. Conidia were tested for viability in non-microwaved suspensions in a mixture (ca. 1:1) of viable and non-viable conidial suspensions, and in the microwaved suspensions that contained all non-viable conidia. No significant differences were observed for the four isolates tested between germination tests on water and agar and viability tests conducted with FDA alone or FDA in combination with PI. One isolate of B. bassiana that had been damaged in storage was also tested. Differences were observed between the actual germination and the percentage of viability determined using FDA or FDA plus PI. Damaged conidia maintained a measure of viability and fluoresced green, but did not fully germinate.     

The physiology of the ovary: Maturation of ovarian granulosa cells and a novel role for antioxidants in the corpus luteum

During folliculogenesis the granulosa cells divide whilst in contact with each other, and so exhibit some of the characteristics of stem cells. In vitro we have shown that bovine granulosa cells from 3–7 mm follicles, like stem cells, divide without the need for a substratum, and produce colonies of cells. Growth factors, bFGF and IGF's, stimulate their division. These cells secrete and assemble a basal lamina, suggesting that the follicular basal lamina is produced by the granulosa cells. They have the morphological characteristics of follicular granulosa cells. Thus this system is ideal for studying the functions of immature granulosa cells because the cells do not spontaneously differentiate or luteinize into luteal cells, as occurs in culture on a substratum. On differentiation into luteal cells in vivo the cells express the steroidogenic enzymes for progesterone production and accumulate β-carotene. During culture of bovine luteal cells we observed that a proportion of the steroidogenic enzyme cholesterol side-chain cleavage cytochrome P450 enzyme became chemically cross-linked to its electron donor, adrenodoxin. P450 enzymes produce oxygen free radicals and oxygen free radicals can cause cross-linking between proteins in close proximity. Cell protect against this damage by the use of antioxidant vitamins. Repleting the cultured luteal cells with β-carotene reduced the amount of cross-linking. We conclude that the high levels of β-carotene in corpora lutea are to protect against damage due to oxygen free radicals generated in the course of progesterone synthesis.     

A stochastic model of bacterial spore germination

A stochastic approach is utilized to develop a model equation capable of describing the time course of germination in a sample of bacterial spores. The time required by a spore to complete the change characteristic of germination consists of an initial interval of no change followed immediately by the duration of the change itself. The experimental basis of the proposed model is the observation that each of these time intervals is distributed over a range of values in a spore sample. Mixed continuous and discrete probabilities are employed in arriving at an average single-spore germination curve which, to a different scale, describes the sample in time.     

Optimized extracellular production of alkaline phosphatase by lky mutants of Escherichia coli K12

Summary Periplasmic-leaky (lky) Hfr mutant strains of Escherichia coli K12, grown in low-phosphate Tris medium, excreted alkaline phosphatase (AP) into the extracellular fluid. The lky207 mutation, which proved to induce the highest AP excretion rate, was transferred to an F^- host, carrying a phoS, T mutation allowing constitutive AP biosynthesis. Use of high-phosphate LB-rich medium for growing this F^- lky strain improved cell biomass, extracellular AP activity and excretion specificity in favour of the enzyme. Physiological studies helped us to develop a new culture medium (LB 8.3) giving higher enzyme and excretion yields. LB 8.3 medium also increased cell viability of lky mutants stored at 4° C.Using optimized culture conditions, the highest extracellular enzyme activity produced by lky mutant 706 was reached in the late stationary growth phase and was equal to 1,400 U/ml of culture medium (i.e., 6 times the intracellular AP content of wild-type strain, Ga15, developed in derepressed conditions); AP released into the extracellular fluid corresponded to 34% of total excreted proteins and was equivalent to a purified enzyme preparation.     

The H+/O ratio of proton translocation linked to the oxidation of succinate by mitochondria

In a recent communication Lehninger and co-workers (Costa, L.E., Reynaferje, B., and Lehninger, A.L. (1984) J. Biol. Chem. 259, 4802-4811) reported values approaching 8 for the H+/O ratio of vectorial proton ejection from rat liver mitochondria respiring with succinate. Here we present a rigorous analysis of these measurements which reveals that they may significantly overestimate the true H+/O stoicheiometry.     

Thyroid hormone: Aldosterone antagonism in cultured epithelial cells

Thyroid hormone (T₃) has been demonstrated to inhibit the action of aldosterone on sodium transport in toad urinary bladder and rat kidney. We have exammined the effect of T₃ on aldosterone action and specific nuclear binding in cultured epithelial cells derived from toad urinary bladder. In cell line TB6-C, addition of 5·10⁻⁸ M T₃ to culture media for up to 3 days results in no change in short-circuit current or transepithelial resistance. This concentration of T₃ completely inhibits the maximal increase in short-circuit current in response to 1·10⁻⁷ M aldosterone. The inhibition can be demonstrated with 18 h preincubation or with simultaneous addition of T₃ and aldosterone. The half-maximal concentration for the inhibition of the aldosterone effect is approx. 5·10⁻⁹ M T₃. T₃ has no effect on cyclic AMP-stimulated short-circuit current in these cells. The effect of T₃ on nuclear binding of [³H]aldosterone was examined using a filtration assay with data analysis by at least-squares curve-fitting program. Best fit was obtained with a model for two binding sites. The dissociation constants for the binding were K′_d1 = (0.82 ± 0.36)·10⁻¹⁰ M and K′_d2 = (3.2±0.60)·10⁻⁸ M.The half-maximal concentration for aldosterone-stimulated sodium transport in these cells is approx. 1·10⁻⁸ M. Analysis of nuclear aldosterone binding in cells preincubated for 18 h with 5·10⁻⁸ M T₃ showed a K′_d1 = (0.15 ± 0.10)·10⁻¹⁰ M and K′_d2 = (3.5 ± 0.10)·10⁻⁸ M. We conclude that T₃ i action of aldosterone on sodium transport at a site after receptor binding in the nucleus.