Characterization of a new and highly distinguishable HLA-A allele in a Spanish family

Correspondence to: J. L. Vicario.     

Fibrolast growth factors in the nervous system

Fibroblast growth factors (FGFs) exhibit widespread mitogenic and neurotrophic activities. Nine members of the family are currently known, and FGF-1 and FGF-2 are present in relatively high levels in CNS. FGF-1 is expressed by a subset of neuronal populations, while FGF-2 is expressed by astrocytes. FGF-1 and FGF-2 lack signal peptides and appear to be present mainly in inracellular compartmens. This suggests that the factors may act as initiators of a repair response after injury. Support for this notion comes from observations that FGF-1 and FGF-2 levels are low during critical phases of development, but high in the adult CNS. A family of transmembrane tyrosine kinase receptors (FGFRs) mediates the effects of FGFs. Four different genes coding for FGF receptors are currently known, three of which are expressed in cell type-specific patterns in the CNS The main receptor variants present in this tissue, however, can by themselves not distinguish between FGF-1 and FGF-2. Additional selectivity may be established by interaction of the FGFs and their receptors with select heparan proteoglycans (HSPGs). Therefore, the precise physiological role of FGFs is determined by the combination of cell type-specific patterns of expression of FGFs, FGFRs and HSPGs together with the mechanisms that regulate the extracellular availability of FGFs. 1994 John Wiley & Sons, Inc.     

Glutamate Dehydrogenase Is Not Essential for Glutamate Formation by Corynebacterium glutamicum

Two Corynebacterium glutamicum strains, one being glutamate dehydrogenase (GDH) negative and the other possessing 11-fold-higher specific GDH activity than the parental wild type, were constructed and used to analyze the role of GDH in C. glutamicum. The results indicate (i) that GDH is dispensable for glutamate synthesis required for growth and (ii) that although a high level of GDH increases the intracellular glutamate pool, the level of GDH has no influence on glutamate secretion.     

Formation of acetyl-CoA in Zymomonas mobilis by a pyruvate dehydrogenase complex

In the gram negative, obligately ethanologenic bacterium Zymomonas mobilis a pyruvate dehydrogenase complex was identified and the complex was enriched from cell extracts. This multienzyme complex is responsible for acetyl-CoA biosynthesis from pyruvate. No activities of related multienzyme complexes, 2-ketoglutarate dehydrogenase and branched chain keto acid dehydrogenase, could be detected.     

High prevalence of a point mutation in the porphobilinogen deaminase gene in Dutch patients with acute intermittent porphyria

Acute intermittent porphyria (AIP) is an autosomal dominant disease characterized by a deficiency of porphobilinogen deaminase (PBGD). Up to now 14 different mutations have been described. In an effort to investigate the molecular epidemiology of AIP we have undertaken a systematic study of different exons of the PBGD gene from a large number of unrelated patients. Here, exon 8 from 82 unrelated Dutch and French AIP patients was examined using single strand confirmation polymorphism analysis (SSCP) after polymerase chain reaction (PCR) amplification. A single base mutation, C to T, at position 346 of the sequence coding for PBGD was observed in 15 Dutch families but in only 1 French family. A simple PCR assay is described to facilitate the diagnosis of this common mutation at the DNA level.     

Oxide-Based Solid-State Batteries: A Perspective on Composite Cathode Architecture

The garnet-type phase Li₇La₃Zr₂O₁₂ (LLZO) attracts significant attention as an oxide solid electrolyte to enable safe and robust solid-state batteries (SSBs) with potentially high energy density. However, while significant progress has been made in demonstrating compatibility with Li metal, integrating LLZO into composite cathodes remains a challenge. The current perspective focuses on the critical issues that need to be addressed to achieve the ultimate goal of an all-solid-state LLZO-based battery that delivers safety, durability, and pack-level performance characteristics that are unobtainable with state-of-the-art Li-ion batteries. This perspective complements existing reviews of solid/solid interfaces with more emphasis on understanding numerous homo- and heteroionic interfaces in a pure oxide-based SSB and the various phenomena that accompany the evolution of the chemical, electrochemical, structural, morphological, and mechanical properties of those interfaces during processing and operation. Finally, the insights gained from a comprehensive literature survey of LLZO–cathode interfaces are used to guide efforts for the development of LLZO-based SSBs.     

Partial purification and properties of a 36-kDa 1-aminocyclopropane-1-carboxylate N-malonyltransferase from mung bean

A 36-kDa 1-aminocyclopropane-1-carboxylate (ACC) N-malonyltransferase, which converts the ethylene precursor ACC into the conjugated derivative malonyl-ACC (MACC), has been isolated from etiolated mung bean ( Vigna radiata ) hypocotyls, and partially purified in a four-step procedure. The enzyme is stimulated about 7-fold by 100 m M K⁺ salts or 0.5 m M Co²⁺ salts, and is inhibited competitively by D-phenylalanine (K_i= 1.3 m M ) and non competitively by CoASH (0.3 m M ). Beside malonyl-CoA, it is capable to use succinyl-CoA as an acyl donor. The 36-kDa enzyme described here exhibits a lower optimum temperature (40°C) and a 7- or 3-fold lower apparent K_m for ACC (68 μ M ) and malonyl-CoA (74 μ M ), respectively, when compared with its 55 kDa isoform already isolated from the same plant material. This data support the idea that several isoforms of ACC N-malonyltransferase exist in plants. These isoforms may play a differential role in regulating the availability of ACC, and consequently the rate of ethylene production, as well as detoxifying cells from D-amino acids.     

13C NMR studies of the fluxes in the central metabolism of Corynebacterium glutamicum during growth and overproduction of amino acids in batch cultures

The carbon flux distribution in the central metabolism of Corynebacterium glutamicum was studied in batch cultures using [1-¹³C]- and [6-¹³C]glucose as substrate during exponential growth as well as during overproduction of l-lysine and l-glutamate. Using the ¹³C NMR data in conjunction with stoichiometric metabolite balances, molar fluxes were quantified and normalised to the glucose uptake rate, which was set to 100. The normalised molar flux via the hexose monophosphate pathway was 40 during exponential growth, whereas it was only 17 during l-glutamate production. During l-lysine production, the normalised hexose monophosphate pathway flux was elevated to 47. Thus, the carbon flux via this pathway correlated with the NADPH demand for bacterial growth and l-lysine overproduction. The normalised molar flux in the tricarboxylic acid cycle at the level of 2-oxoglutarate dehydrogenase was 100 during exponential growth and 103 during l-lysine secretion. During l-glutamate formation, the normalised flux through the tricarboxylic acid cycle was reduced to 60. In contrast to earlier NMR studies with C. glutamicum, no significant activity of the glyoxylate pathway could be detected. All experiments indicated a strong in vivo flux from oxaloacetate back to phosphoenolpyruvate and/or pyruvate, which might be due to phosphoenolpyruvate carboxykinase activity in C. glutamicum.