Distribution of C22-, C24- and C26-α-Unit-Containing Mycolic Acid Homologues in Mycobacteria

There are three mycolic acid homologues with C₂₂-, C₂₄- and C₂₆-α-units in Mycobacterium. In order to reveal the composition and distribution of these homologues in each subclass and molecular species of mycolic acids and to compare them with the composition of constitutive non-polar fatty acids (free and bound forms), we have separated non-polar fatty acids and each subclass of mycolic acids from 21 mycobacterial species by thin-layer chromatography, and analyzed non-polar fatty acid methyl esters by gas chromatography (GC) and the cleavage products of methyl mycolate by pyrolysis GC. We further performed mass chromatographic analysis of trimethylsilyl (TMS) ether derivatives of mycolic acid methyl esters by monitoring [B-29]⁺ ions (loss of CHO from the α-branched-chain structure of mycolic acids) of m/z 426, 454 and 482 which are attributed to C₂₂-, C₂₄- and C₂₆-α-units of TMS ether derivatives of methyl mycolates, respectively, (Kaneda, K. et al, J. Clin. Microbiol. 24: 1060-1070, 1986). By pyrolysis GC, C_22:0, C_24:0 and C_26:0 fatty acid methyl esters generated by the C₂-C₃ cleavage of C₂₂-, C₂₄- and C₂₆-α-unit-containing mycolic acid methyl esters, respectively, were detected. Their proportion was almost the same among subclasses of mycolic acids in every Mycobacterium and also similar to the proportion of constitutive non-polar C_22:0, C_24:0 and C_26:0 fatty acids. By mass chromatography, the composition and distribution of C₂₂- and C₂₄-α-unit-containing homologues were revealed to be similar between α- and α'-mycolic acids in every Mycobacterium. We further analyzed in detail M. vaccae and demonstrated that the mass chromatogram of C₂₂-α-unit-containing homologue was analogous in shape to that of the C₂₄-α-unit-containing one, with the latter mass chromatogram being up-shifted from the former by two carbon numbers, in every subclass of α-, α'-, keto and dicarboxy mycolic acids. The present study suggests that the compositions of three homologues of both mycolic acids and constitutive non-polar fatty acids, which are characteristic to each mycobacterial species, may reflect the proportion of the amount of free C_22:0, C_24:0 and C_26:0 fatty acids synthesized in the cell. It is further demonstrated that intermolecular condensation of two fatty acids which become α- and β-units of mycolic acids will occur independently of the carbon chain length or kinds of polar moieties of fatty acids.     

Synthesis of tetracontapeptide--a hypothetical evolutionary precursor of calcium-binding proteins. I. Synthesis of (1-9), (10-14), (15-20), (21-26), (29-33), (34-40) fragments

Fragments (1-9), (10-14), (15-20), (21-26), (29-33) and (34-40) of a tetracontapeptide hypothetical ancestor of calcium-binding proteins were synthesised with the use of pentafluorophenyl esters. Formation of a succinimide derivative was detected during synthesis of fragment (15-20) containing Asp(OBzl)-Gly sequence. To avoid this side process, tert-butylprotecting group was used instead of benzyl group. alpha-Carboxyls of C-terminal amino acids were protected by phenacyl group.     

Purification of Drosophila ribosomal proteins. Isolation of proteins S8, S13, S14, S16, S19, S20/L24, S22/L26, S24, S25/S27, S26, S29, L4, L10/L11, L12, L13, L16, L18, L19, L27, 1, 7/8, 9, and 11

The proteins of Drosophila melanogaster embryonic ribosomes were separated into seven groups (A80 through G80) by stepwise elution from carboxymethylcellulose with lithium chloride at pH 6.5 by procedures previously described [Chooi, W. Y., Sabatini, L. M., MacKlin, M. D., & Fraser, W. (1980) Biochemistry 19, 1425-1433]. Three relatively acidic proteins, S14, S25/S27, and 7/8, have now been isolated from group A80 by ion-exchange chromatog raphy on carboxymethylcellulose eluted with a linear gradient of lithium chloride at pH 4.2. Fractions containing the relatively basic proteins (groups B80 through G80) were furher combined into a total of 24 "pools". The criterion for combination was the migration patterns in one-dimensional polyacrylamide gels containing sodium dodecyl sulfate (NaDodS04) of every fifth fraction from the carboxymethylcellulose column. Each pool contained between 1 and 12 major proteins. Proteins S8, S13, S16, S19, S20/L24, S22/L26, S24, S26, S29, L4, L10/L11, L12, L13, L16, L18, L19, L27, 1, 9, and 11 have now been isolated from selected pools by gel filtration through Sephadix G-100. The amount of each protein recovered from a starting amount of 1.8 g of total 80S proteins varied form 0.2 to 10.8 mg. Five proteins had no detectable contamination, and in each of the others the impurities were no greater than 9%. The amino acid composition of the individual purified proteins was determined. The molecular weights of the proteins were estimated by polyacrylamide gel electrophoresis in NaDodSO4.     

Three chromosome abnormalities (trisomy 21, XXY, and a de nova reciprocal translocation) in a child with 48, XXY, + 21,T(6;10)(P22-24;P12).

An infant with chromosomally normal parents was found to have double aneuploidy and a reciprocal translocation between chromosomes number 6 and 10. This cooccurrence may represent a very rare coincidence or may indicate that primary nondisjunction and chromosome rearrangements may be more than coincidentally related.     

24 epsilon-Methyl-5 alpha-cholestane-3 beta,5,6 beta,22r,24-pentol 6-acetate: new polyhydroxylated sterol from the soft coral Asterospicularia randalli

A monoacetylated pentahydroxylated sterol has been isolated from the soft coral Asterospicularia randalli collected at Guam Is. in the Pacific. The unusual feature of this sterol is the presence of a hydroxyl group at C-22. The structure was determined by spectral analyses of the new sterol and several transformation products. Proton-carbon correlated spectra were used to make 13C chemical shift assignments.     

RCAI-17, 22, 24-26, 29, 31, 34-36, 38-40, and 88, the analogs of KRN7000 with a sulfonamide linkage: their synthesis and bioactivity for mouse natural killer T cells to produce Th2-biased cytokines

RCAI-17, 22, 24-26, 29, 31, 34-36, 38-40, and 88, the analogs of KRN7000 with a sulfonamide linkage instead of an amide bond, were synthesized to examine their bioactivity for mouse natural killer (NK) T cells. RCAI-17, 22, 24-26, 29, 31, 34-36, and 88 are the aromatic sulfonamide analogs, while RCAI-39 and 40 are the aliphatic ones. RCAI-38 is a C-galactoside analog of RCAI-26, which is the p-toluenesulfonamide analog of KRN7000. According to their bioassay, these sulfonamide analogs were shown to be the stimulants of mouse NKT cells to induce the production of Th2-biased cytokines in vitro, while RCAI-38 did not induce any cytokine production.     

Astrocytes, Not Neurons, Produce Docosahexaenoic Acid (22:6ω-3) and Arachidonic Acid (20:4ω-6)

Elongated, highly polyunsaturated derivatives of linoleic acid (18:2 omega-6) and linolenic acid (18:3 omega-3) accumulate in brain, but their sites of synthesis are not fully characterized. To investigate whether neurons themselves are capable of essential fatty acid elongation and desaturation or are dependent upon the support of other brain cells, primary cultures of rat neurons and astrocytes were incubated with [1-14C] 18:2 omega-6, [1-14C]20:4 omega-6, [1-14C]18:3 omega-3, or [1-14C]20:5 omega-3 and their elongation/desaturation products determined. Neuronal cultures were routinely incapable of producing significant amounts of delta 4-desaturase products. They desaturated fatty acids very poorly at every step of the pathway, producing primarily elongation products of the 18- and 20-carbon precursors. In contrast, astrocytes actively elongated and desaturated the 18- and 20-carbon precursors. The major metabolite of 18:2 omega-6 was 20:4 omega-6, whereas the primary products from 18:3 omega-3 were 20:5 omega-3, 22:5 omega-3, and 22:6 omega-3. The majority of the long-chain fatty acids formed by astrocyte cultures, particularly 20:4 omega-6 and 22:6 omega-3, was released into the extracellular fluid. Although incapable of producing 20:4 omega-6 and 22:6 omega-3 from precursor fatty acids, neuronal cultures readily took up these fatty acids from the medium. These findings suggest that astrocytes play an important supportive role in the brain by elongating and desaturating omega-6 and omega-3 essential fatty acid precursors to 20:4 omega-6 and 22:6 omega-3, then releasing the long-chain polyunsaturated fatty acids for uptake by neurons.     

Age-related maculopathy: a genomewide scan with continued evidence of susceptibility loci within the 1q31, 10q26, and 17q25 regions

Age-related maculopathy (ARM), or age-related macular degeneration, is one of the most common causes of visual impairment in the elderly population of developed nations. In a combined analysis of two previous genomewide scans that included 391 families, containing up to 452 affected sib pairs, we found linkage evidence in four regions: 1q31, 9p13, 10q26, and 17q25. We now have added a third set of families and have performed an integrated analysis incorporating 530 families and up to 736 affected sib pairs. Under three diagnostic models, we have conducted linkage analyses using parametric (heterogeneity LOD [HLOD] scores under an autosomal dominant model) and nonparametric (Sall statistic) methods. There is ongoing evidence of susceptibility loci within the 1q31, 10q26, and 17q25 regions. If we treat the third set of families as a replication set, then two regions (10q26 and 17q25) are replicated, with LOD scores >1.0. If we pool all our data together, then four regions (1q31, 2q14.3, 10q26, and 17q25) show HLOD or Sall scores > or =2.0. Within the 1q31 region, we observed an HLOD of 2.72 (genomewide P=.061) under our least stringent diagnostic model, whereas the 17q25 region contained a maximal HLOD of 3.53 (genomewide P=.007) under our intermediate diagnostic model. We have evaluated our results with respect to the findings from several new independent genomewide linkage studies and also have completed ordered subset analyses (OSAs) with apolipoprotein E alleles, smoking history, and age at onset as stratifying covariates. The OSAs generate the interesting hypothesis that the effect of smoking on the risk of ARM is accentuated by a gene in the 10q26 region--a region implicated by four other studies.     

Post-mortem studies on two patients with 1-2 band cytogenetic deletions: 10q26----qter and r(9)(p24q34)

Two severely retarded males with unbalanced karyotypes Case 1--(45,XY,--10,--15, + der(10)t,(10; 15) (q26; q13) and Case 2--46,XY,r(9) (p24q34) died at the ages of 24 and 38 years respectively. At post-mortem, a post-ductal coarctation of the aorta and a lump kidney were found in the first case. Brain pathology was normal in the first case and apart from a smaller size, was structurally normal in the second case.