Inactivation of ccmO in Synechococcus sp. Strain PCC 7942 Results in a Mutant Requiring High Levels of CO(2)

Inactivation of ccmO in Synechococcus sp. strain PCC 7942 resulted in a mutant which possesses aberrant carboxysomes and a normal inorganic carbon uptake capability but a reduced ability to photosynthetically utilize the internal inorganic carbon pool. Consequently, it exhibits low apparent photosynthetic affinity for extracellular inorganic carbon and demands high levels of CO(2) for growth.     

Duplication of the short arm of the X chromosome in mother and daugther

An 11-year-old girl with short stature, mental retardation, and mild dysmorphic features was found to have an inverted duplication of most of the short arm of the X chromosome [dic inv dup(X)(qterp22.3: :p22.3 cen:)]. Her mother, who is also short and retarded, carries the same duplication. Fluorescence in situ hybridization with an X chromosome library, and with X centromerespecific alpha satellite and telomere probes, was useful in characterizing the duplication. In most females with structurally abnormal X chromosomes, the abnormal chromosome is inactivated. Although the duplicated X was consistently late replicating in the mother, X chromosome inactivation studies in the proband indicated that in 11% of her lymphocytes the duplicated X was active.     

Development of quasi-multicellular bodies of Treponema denticola

The formation of quasi-multicellular bodies of Treponema denticola was analysed using different electron microscopical methods. These bacteria could develop four different conformations: (i) normal helical forms; (ii) twisted spirochetes, forming plaits; (iii) twisted spirochetes, forming club-like structures; (iv) spherical bodies in different size. Treponemes within spherical bodies, plaits, and clubs proved to be enclosed in a common outer sheath in which the normal arrangement of their axial flagella was lost. The development of the quasi-multicellular bodies starting from the monoforme spirochetes was elucidated and this morphogenetic process is illustrated by a schematic drawing. Factors which might be involved in the induction of the structures are discussed and their possible pathogenetic importance is considered.     

Cis-regulatory sequences leading to female-specific expression of yolk protein genes 1 and 2 in the fat body of Drosophila melanogaster

We determined the physical linkage of six mouse Hox3 homeobox sequences, including a new homeobox sequence (Hox3.5), by analysis of overlapping genomic clones. Additionally, we defined the locations of Hox 1.7 and Hox 1.8 in the Hox 1 cluster. Analysis of the expression patterns of Hox 3.6 and Hox 3.5 during embryogenesis revealed that the relationship between relative position in the Hox 3 cluster and expression domain along antero-posterior axis appears similar to that seen for members of the other Hox clusters.     

Properties and function of malate enzyme from Pseudomonas putida

Malate enzyme (l-malate : NADP⁺ oxidoreductase (oxalacetate-decarboxylating, EC 1.1.1.40)) has been purified from Pseudomonas putida to 99 per cent homogeneity by heat, ammonium suphate fractionation, gel filtration and anion exchange chromatography. Sodium dodecylsulphate-(SDS)-polyacrylamide disc gel electrophoresis analysis showed an approximate tetrameric subunit with a molecular weight of 52,000. The purified enzyme showed a pH optimum between 8.0 and 8.5 (for Tris-HCl buffer) and required bivalent cations for catalysis ; monovalent ions like K⁺ and NH₄⁺ acted as very effective activators. The temperature-activity relationship for the malate enzyme from 35–80 °C showed broken Arrhenius plots with an inflexion at 65 °C. The enzyme halflife was 30s at 85 °C.The enzyme showed hyperbolic kinetics for both substrates with apparent K_m values of 4.0 × 10⁻⁴ M and 2.3 × 10⁻⁵ M for l-malate and NADP⁺ respectively. From the study of the effects of some compounds on the enzyme, the physiological significance of those produced by fumarate, succinate and oxalacetate can be emphasized.     

A tumor promoter stimulates phosphorylation on tyrosine

The tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate is mitogenic for normal chicken embryo fibroblasts and also causes these cells to express transiently many properties of cells transformed by Rous sarcoma virus. Since some mitogenic hormones stimulate a tyrosine-specific protein kinase activity, and since the transforming protein of RSV is a tyrosine-specific protein kinase, we have examined whether TPA also stimulates protein phosphorylation on tyrosine. We report here that TPA treatment of normal cells resulted in a very rapid phosphorylation on tyrosine of a protein peak of Mr 40 to 43 kilodaltons. Thus, a similar biochemical activity (tyrosine phosphorylation) is associated with the action of polypeptide mitogenic hormones, Rous sarcoma virus and a tumor promoter. In addition, TPA treatment resulted in rapid changes in phosphorylation of proteins on serine and threonine.     

Quantitative inheritance and barriers to crossability in Cicer arietinum L.

Summary Three different diallel crosses were studied in Cicer arietinum; two of size 6×6, one within each of the two botanical groups macrosperma and microsperma of the cultivated subspecies, and one of 9×9 involving lines covering most of the morphological variation of chickpea. Barriers to crossability present neither a botanical nor a geographical pattern, being probably a direct consequence of interactions between genotypes. The genetic systems of twelve quantitative characters were analysed. Full dominance in a negative sense (small values dominant) is shown by leaflet length, width and shape index, rachis length, leaflet density on the rachis and pod length. Full dominance in a positive sense is shown by seeds per pod. Overdominance (in a positive sense) is evident for pods, seeds and yield per plant. Weak reciprocal differences were manifested by pod length, and pods, seeds and yield per plant. The system controlling number of leaflets per leaf is not clear. Dominance of primitive over selected characters seems to be the rule. As far as the environmental effects have permitted the analysis, no differences in genetic systems were observed between botanical groups.     

Elongation factor Tu-induced conformational changes of ribosomes detected by iodination

The effect of elongation factor (EF) Tu, bound to the ribosome with the help of poly(uridylic) acid, Phe-tRNA and guanyl-5-yl methylene diphosphonate, on the conformation and/or chemical environment of ribosomal proteins has been examined using, as a probe, protein iodination. Ribosomes complexed only with poly(uridylic acid) and Phe-tRNA have been used as a control. EF-Tu on the ribosome significantly increases the iodination of proteins S7, S10 and L3 and decreases that of S21 and L18.     

Modulation of 25-hydroxyvitamin D3-24-hydroxylase by aminophylline: a cytochrome P-450 monooxygenase system.

The enzymatic activity of human erythrocyte pyruvate kinase was found to decrease on incubation of the purified enzyme with red blood cell ghosts, ATP and cAMP. If $\text{[}{}^{32}\text{P]γATP}$ was used radioactivity was found associated with the protein after gel electrophoresis. Various effectors protected the enzyme against phosphorylation. Treatment of the modified enzyme with a protein phosphatase restored enzymatic activity and also caused the loss of the radioactive label. Modification of the pyruvate kinase in this way altered the affinity of the enzyme for one of its substrates (phosphoenolpyruvate), but the binding of the other substrate (ADP) was unaffected.     

Malformed genitalia in the 47,XYY genotype.

A 5 10/12 year-old boy with a 47,XYY karyotype, micropenis, scrotal hypospadias and right testicular regression is described. Normal for age basal plasma testosterone levels which increased after hCG stimulation were interpreted as an adequate response of the left testicular Leydig cells. The review of similar cases did not permit definite conclusions concerning the relationship between the abnormal genitalia and the XYY karyotype.