Marc Reynders

Spikelet structure and development in Cyperoideae (Cyperaceae): a monopodial general model based on ontogenetic evidence.

BACKGROUND AND AIMS In Cyperoideae, one of the two subfamilies in Cyperaceae, unresolved homology questions about spikelets remained. This was particularly the case in taxa with distichously organized spikelets and in Cariceae, a tribe with complex compound inflorescences comprising male (co)florescences and deciduous female single-flowered lateral spikelets. Using ontogenetic techniques, a wide range of taxa were investigated, including some controversial ones, in order to find morphological arguments to understand the nature of the spikelet in Cyperoideae. This paper presents a review of both new ontogenetic data and current knowledge, discussing a cyperoid, general, monopodial spikelet model. METHODS Scanning electron microscopy and light microscopy were used to examine spikelets of 106 species from 33 cyperoid genera. RESULTS Ontogenetic data presented allow a consistent cyperoid spikelet model to be defined. Scanning and light microscopic images in controversial taxa such as Schoenus nigricans, Cariceae and Cypereae are interpreted accordingly. CONCLUSIONS Spikelets in all species studied consist of an indeterminate rachilla, and one to many spirally to distichously arranged glumes, each subtending a flower or empty. Lateral spikelets are subtended by a bract and have a spikelet prophyll. In distichously organized spikelets, combined concaulescence of the flowers and epicaulescence (a newly defined metatopic displacement) of the glumes has caused interpretational controversy in the past. In Cariceae, the male (co)florescences are terminal spikelets. Female single-flowered spikelets are positioned proximally on the rachis. To explain both this and the secondary spikelets in some Cypereae, the existence of an ontogenetic switch determining the development of a primordium into flower, or lateral axis is postulated.

Taxonomy of the Peperomia species (Piperaceae) with pseudo‐epiphyllous inflorescences, including four new species

Twelve of the estimated 1500–1700 taxa in Peperomia show a particular feature: their terminal inflorescences seem to originate from the base of a leaf blade as a result of the presence of a sessile leaf at the base of these inflorescences. Three of these 12 taxa occur in Ecuador and four species are reported from Colombia. From Peru, two species are known from historical herbarium collections, and three other species are new to science. One new species is described from Bolivia. Collections of all 12 species are quite rare and, in the past, their identification seems to have been rather problematic. Previous authors have referred to these inflorescences as epiphyllous but, as shown here, this is not a correct description. To make a clear distinction from genuine epiphyllous inflorescences, the term ‘pseudo‐epiphyllous’ is proposed. In addition to the publication of four new species of Peperomia, emended descriptions are provided for the other species, synonymy is treated, and lectotypes are designated. The architecture of the plants is discussed and a key to the 12 species is provided. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157, 177–196.

Cyperus limiticola, a New Name for a Madagascan Cyperus (Cyperaceae)

ABSTRACT There is a need to propose a new name in Cyperus L. for C. paucispiculatus Chermezon because the name currently used is an illegitimate later homonym of C. paucispiculatus Böckeler. A new name, C. limiticola Larridon & Reynders, is provided here.

Bulbostylis medusae (Cyperaceae), a New Species from Venezuela

ABSTRACT Bulbostylis medusae Prata, Reynders & Goetghebeur from Venezuela is fully described and illustrated. This species differs from all other South American Bulbostylis Kunth species by the combination of long-ciliated leaf sheaths, leaf apices, bracts, and spikelet axes. The new species resembles B. sellowiana (Kunth) Palla, and a comparison of the two species is made.

Kyllinga beninensis (Cyperaceae), a New Species from Bénin

ABSTRACT Kyllinga beninensis Samain, Reynders & Goetghebeur, a new species of Cyperaceae from the Borgou-Sud region of Bénin, is fully described and illustrated. This species can be recognized by the slender habit with swollen stem base, the tiny white head consisting of a single spike, and the spikelets with two glumes and one flower. Morphological differences with the species K. microbulbosa Lye from East Africa, to which K. beninensis bears a superficial resemblance, are discussed.

Research noteTigecycline-induced inhibition of mitochondrial DNA translation may cause lethal mitochondrial dysfunction in humans

BACKGROUND A 65-year-old patient developed an unexplained and ultimately lethal metabolic acidosis under prolonged treatment with tigecycline. Tigecycline is known to have a selective inhibitory effect on eukaryotic mitochondrial translation. The underlying molecular mechanisms of the metabolic acidosis in this patient were explored. METHODS Oxidative phosphorylation system (OXPHOS) analysis, blue native polyacrylamide gel electrophoresis followed by in-gel activity staining in mitochondria, molecular analysis of mitochondrial DNA (mtDNA) for genomic rearrangements and sequencing of the rRNA genes was performed on the subjects skeletal muscle. RESULTS OXPHOS analysis revealed a combined deficiency of the complexes I, III, IV and V, with a preserved function of complex II (encoded by nuclear DNA), thus demonstrating a defective mtDNA translation. There were no known underlying mitochondrial genetic defects. The patient had a (m.1391T>A) variant within the 12SrRNA gene in heteroplasmy (50-60%). CONCLUSIONS This patient developed an ultimately lethal mitochondrial toxicity while receiving prolonged treatment with tigecycline, which was caused by a defective translation of the mtDNA. Tigecycline is known to suppress eukaryotic mitochondrial DNA translation, but until now this effect has been considered to be clinically insignificant. The observations in this patient suggest a clinically significant mitochondrial toxicity of tigecycline in this patient, and warrant further investigation.

Tigecylcine induced inhibition of mitochondrial mtDNA translation may cause a lethal mitochondrial dysfunction in human

BACKGROUND A 65-year-old patient developed an unexplained and ultimately lethal metabolic acidosis under prolonged treatment with tigecycline. Tigecycline is known to have a selective inhibitory effect on eukaryotic mitochondrial translation. The underlying molecular mechanisms of the metabolic acidosis in this patient were explored. METHODS Oxidative phosphorylation system (OXPHOS) analysis, blue native polyacrylamide gel electrophoresis followed by in-gel activity staining in mitochondria, molecular analysis of mitochondrial DNA (mtDNA) for genomic rearrangements and sequencing of the rRNA genes was performed on the subjects skeletal muscle. RESULTS OXPHOS analysis revealed a combined deficiency of the complexes I, III, IV and V, with a preserved function of complex II (encoded by nuclear DNA), thus demonstrating a defective mtDNA translation. There were no known underlying mitochondrial genetic defects. The patient had a (m.1391T>A) variant within the 12SrRNA gene in heteroplasmy (50-60%). CONCLUSIONS This patient developed an ultimately lethal mitochondrial toxicity while receiving prolonged treatment with tigecycline, which was caused by a defective translation of the mtDNA. Tigecycline is known to suppress eukaryotic mitochondrial DNA translation, but until now this effect has been considered to be clinically insignificant. The observations in this patient suggest a clinically significant mitochondrial toxicity of tigecycline in this patient, and warrant further investigation.

Tigecycline-induced inhibition of mitochondrial DNA translation may cause lethal mitochondrial dysfunction in humans

BACKGROUND A 65-year-old patient developed an unexplained and ultimately lethal metabolic acidosis under prolonged treatment with tigecycline. Tigecycline is known to have a selective inhibitory effect on eukaryotic mitochondrial translation. The underlying molecular mechanisms of the metabolic acidosis in this patient were explored. METHODS Oxidative phosphorylation system (OXPHOS) analysis, blue native polyacrylamide gel electrophoresis followed by in-gel activity staining in mitochondria, molecular analysis of mitochondrial DNA (mtDNA) for genomic rearrangements and sequencing of the rRNA genes was performed on the subjects skeletal muscle. RESULTS OXPHOS analysis revealed a combined deficiency of the complexes I, III, IV and V, with a preserved function of complex II (encoded by nuclear DNA), thus demonstrating a defective mtDNA translation. There were no known underlying mitochondrial genetic defects. The patient had a (m.1391T>A) variant within the 12SrRNA gene in heteroplasmy (50-60%). CONCLUSIONS This patient developed an ultimately lethal mitochondrial toxicity while receiving prolonged treatment with tigecycline, which was caused by a defective translation of the mtDNA. Tigecycline is known to suppress eukaryotic mitochondrial DNA translation, but until now this effect has been considered to be clinically insignificant. The observations in this patient suggest a clinically significant mitochondrial toxicity of tigecycline in this patient, and warrant further investigation.

LOW YIELD BY MOLECULAR DETECTION OF CHLAMYDOPHILA PNEUMONIAE IN RESPIRATORY SAMPLES IN BELGIUM QUESTIONING ITS ETIOLOGICAL ROLE IN RESPIRATORY TRACT INFECTIONS

Abstract The actual burden of respiratory infections due to Chlamydophila pneumoniae is difficult to assess due to the major differences in positivity rates between PCRand serology-based methods. The aim of the current study was to objectively analyse the yield of PCRs for the detection of C. pneumoniae in respiratory samples and to evaluate the additional value of performing laboratory diagnosis for C. pneumoniae in a setting of respiratory infection. The data based on routine analysis of respiratory samples with request for C. pneumoniae detection were collected from 4 large Belgian hospitals during 2 consecutive years. In total 3560 respiratory samples have been analysed and overall only 7 samples (0.2%) were found positive. Based on these observations, the critical evaluation of the actual role of C. pneumoniae in the etiology of lower respiratory infections and consequently of the extensive use of diagnostic tools for the detection of C. pneumoniae is needed.

Two New Species of Cyperus (Cyperaceae) from the Zambezian Region of Africa

Abstract Cyperus absconditicoronatus Bauters, Reynders & Goetgh. and C. unispicatus Bauters, Reynders & Goetgh., two new species of Cyperus L. (Cyperaceae) from Angola and Zambia, are recognized. Cyperus absconditicoronatus is a tall species (55–100 cm) characterized by a scaled rhizome, a single terminal capitulum, a ciliated spikelet bract, and deciduous spikelets. Cyperus unispicatus can be recognized by a swollen and fibrous stem base growing from slender rhizomes, a single terminal spike, and short involucral bracts. The taxa are described and illustrated, and differences with the closest resembling species are discussed.