THE TAXONOMIC POSITION OF PAPUODENDRON C.T. WHITE AS ELUCIDATED BY ANATOMICAL CHARACTERS

When, in 1946, White described Papuodendron lepidotum from New Guinea, he apparently hesitated to incorporate this species in the Bombacaceae

NEW THINKING IN PUNT MORPHOLOGY

This note is to reflect the thoughts, practical work and hopes of two workers in the Netherlands who are angaged in this branch of science, Dr. B.M.Moeliono of the Botanical laboratory at Groningen, and myself at the Rijskherbarium at laide

Structural and functional consequences of removing the N-terminal domain from the magnesium chelatase ChlH subunit of Thermosynechococcus elongatus

Magnesium chelatase (MgCH) initiates chlorophyll biosynthesis by catalysing the ATP-dependent insertion of Mg2+ into protoporphyrin. This large enzyme complex comprises ChlH, I and D subunits, with I and D involved in ATP hydrolysis, and H the protein that handles the substrate and product. The 148 kDa ChlH subunit has a globular N-terminal domain attached by a narrow linker to a hollow cage-like structure. Following deletion of this ~18 kDa domain from the Thermosynechoccus elongatus ChlH, we used single particle reconstruction to show that the apo- and porphyrin-bound forms of the mutant subunit consist of a hollow globular protein with three connected lobes; superposition of the mutant and native ChlH structures shows that, despite the clear absence of the N-terminal ‘head’ region, the rest of the protein appears to be correctly folded. Analyses of dissociation constants shows that the ΔN159ChlH mutant retains the ability to bind protoporphyrin and the Gun4 enhancer protein, although the addition of I and D subunits yields an extremely impaired active enzyme complex. Addition of the Gun4 enhancer protein, which stimulates MgCH activity significantly especially at low Mg2+ concentrations, partially reactivates the ΔN159ChlH–I–D mutant enzyme complex, suggesting that the binding site or sites for Gun4 on H do not wholly depend on the N-terminal domain

Unchaining miniBacillus PG10:Relief of FlgM-mediated repression of autolysin genes

Cell chaining in Bacillus subtilis is naturally observed in a subset of cells during exponential growth and during biofilm formation. However, the recently constructed large-scale genome-minimized B. subtilis strain PG10 displays a severe and permanent defect in cell separation, as it exclusively grows in the form of long filaments of nonseparated cells. In this study, we investigated the underlying mechanisms responsible for the incomplete cell division of PG10 by genomic and transcriptomic analyses. Repression of the SigD regulon, including the major autolysin gene lytF, was identified as the cause for the cell separation problem of PG10. It appeared that SigD-regulated genes are downregulated in PG10 due to the absence of the flagellar export apparatus, which normally is responsible for secretion of FlgM, the anti-sigma factor of SigD. Although mild negative effects on growth and cell morphology were observed, deletion of flgM could revert the aberrant cell-chaining phenotype and increased transformation efficiency. Interestingly, our work also demonstrates the occurrence of increased antisense transcription of slrR, a transcriptional repressor of autolysin genes, in PG10 and provides further understanding for this observation. In addition to revealing the molecular basis of the cell separation defect in PG10, our work provides novel targets for subsequent genome reduction efforts and future directions for further optimization of miniBacillus PG10. IMPORTANCE Reduction of the size of bacterial genomes is relevant for understanding the minimal requirements for cellular life as well as from a biotechnological point of view. Although the genome-minimized Bacillus subtilis strain PG10 displays several beneficial traits as a microbial cell factory compared to its parental strain, a defect at the final stage of cell division was introduced during the genome reduction process. By genetic and transcriptomic analyses, we identified the underlying reasons for the cell separation problem of PG10. In addition to enabling PG10 to grow in a way similar to that of B. subtilis wild-type strains, our work points toward subsequent targets for fine-tuning and further reduction of the genome of PG10. Moreover, solving the cell separation defect facilitates laboratory handling of PG10 by increasing the transformation efficiency, among other means. Overall, our work contributes to understanding and improving biotechnologically attractive minimal bacterial cell factories

MiniBacillus PG10 as a Convenient and Effective Production Host for Lantibiotics

Efficient bacterial cell factories are important for the screening and characterization of potent antimicrobial peptides such as lantibiotics. Although lantibiotic production systems have been established in Lactococcus lactis and Escherichia coli, the industrial workhorse Bacillus subtilis has been left relatively unexplored as a lantibiotic production host. Therefore, we tested different B. subtilis strains for their ability to produce lantibiotic peptides by using the subtilin modification and transport enzymes derived from the natural subtilin producer B. subtilis ATCC 6633. Our study shows that although B. subtilis ATCC 6633 and 168 are able to produce various processed lantibiotic peptides, an evident advantage of using either the 8-fold protease-deficient strain WB800 or the genome-minimized B. subtilis 168 strain PG10 is the lack of extracellular serine protease activity. Consequently, leader processing of lantibiotic precursor peptides is circumvented and thus potential toxicity toward the production host is prevented. Furthermore, PG10 provides a clean secondary metabolic background and therefore appears to be the most promising B. subtilis lantibiotic production host. We demonstrate the production of various lantibiotic precursor peptides by PG10 and show different options for their in vitro activation. Our study thus provides a convenient B. subtilis-based lantibiotic production system, which facilitates the search for novel antimicrobial peptides

Arthropathy on X-rays in 363 persons with hemophilia: long-term development, and impact of birth cohort and inhibitor status

BACKGROUND: Arthropathy following repeated bleeding is common in persons with hemophilia. Since the introduction of prophylaxis, treatment has intensified and joint health has improved. However, data on the long-term development of arthropathy are still scant. OBJECTIVES: To evaluate long-term arthropathy development since the introduction of prophylaxis according to birth cohort, hemophilia severity, and inhibitor status. METHODS: This single-center historic cohort study included persons with severe and moderate hemophilia A and hemophilia B born between 1935 and 2005. Arthropathy on X-rays was evaluated using the Pettersson score. Patient and joint characteristics were studied per birth cohort (1990) and compared according to hemophilia severity. The distribution of affected joints and cumulative incidence of arthropathy were analyzed. The association of Pettersson score with birth cohort and inhibitor characteristics was explored using multivariable regression analyses adjusted for age at evaluation. RESULTS: In total, 1064 X-rays of 363 patients were analyzed. Of persons with severe hemophilia (n = 317, 87.3%), 244 (77.0%) developed arthropathy. Prophylaxis was started at younger ages over time, from a median of 18 to 2.1 years, and concomitantly, arthropathy decreased in consecutive birth cohorts. Ankles were most commonly affected in 188 of 258 (72.9%) patients. Persons with moderate hemophilia (n = 46, 12.7%) had a lower risk of arthropathy (27/46 [58.7%]), but a reduction over time was less pronounced. In the multivariable analyses, birth cohort and age at evaluation were predictors for the development of arthropathy, while inhibitor status showed no association. CONCLUSION: The development and severity of arthropathy have decreased over the past decades. However, patients have remained at risk for developing arthropathy, especially in their ankles

A case report of a blueberry muffin baby caused by congenital self-healing indeterminate cell histiocytosis

Background: Blueberry muffin is a descriptive term for a neonate with multiple purpuric skin lesions. Many causes are known, amongst them life-threatening diseases like congenital infections or leukemia. Indeterminate cell histiocytosis (ICH) is an exceptionally rare cause of blueberry muffin rash. ICH is a histiocytic disorder which can be limited to the skin or can present with systemic involvement. A mutation that has been described in histiocytic disorders is a MAP2K1 mutation. In ICH, this mutation has previously been described in merely one case. Case presentation: A term male neonate was admitted to the neonatology ward directly after birth because of a blueberry muffin rash. ICH was diagnosed on skin biopsy. The lesions resolved spontaneously. The patient is currently 3 years old and has had no cutaneous lesions or systemic involvement so far. This disease course is similar to that of the Hashimoto-Pritzker variant of LCH. Conclusions: ICH can manifest in neonates as resolving skin lesions. It is limited to the skin in most cases, but systemic development is possible. Therefore, it is essential to confirm the diagnosis with a biopsy before the lesions resolve and to monitor these patients closely with routine follow-up.</p