Verbascum eskisehirensis sp. nov. (Scrophulariaceae) from central Anatolia, Turkey

Verbascum eskisehirensis Karavel., Ocak & Ekici sp. nov. (sect. Bothrosperma Murb.) is described and illustrated from Turkey. This new species is confined to B3 Eskisehir in central Anatolia. A morphological comparison is made with the closely related species; V. oreophilum K. Koch and V. pyramidatum M. Bieb. In addition, a cluster analysis was conducted and a distribution map of the new species and the related species is also given.     

Severely incapacitating mutations in patients with extreme short stature identify RNA-processing endoribonuclease RMRP as an essential cell growth regulator

The growth of an individual is deeply influenced by the regulation of cell growth and division, both of which also contribute to a wide variety of pathological conditions, including cancer, diabetes, and inflammation. To identify a major regulator of human growth, we performed positional cloning in an autosomal recessive type of profound short stature, anauxetic dysplasia. Homozygosity mapping led to the identification of novel mutations in the RMRP gene, which was previously known to cause two milder types of short stature with susceptibility to cancer, cartilage hair hypoplasia, and metaphyseal dysplasia without hypotrichosis. We show that different RMRP gene mutations lead to decreased cell growth by impairing ribosomal assembly and by altering cyclin-dependent cell cycle regulation. Clinical heterogeneity is explained by a correlation between the level and type of functional impairment in vitro and the severity of short stature or predisposition to cancer. Whereas the cartilage hair hypoplasia founder mutation affects both pathways intermediately, anauxetic dysplasia mutations do not affect B-cyclin messenger RNA (mRNA) levels but do severely incapacitate ribosomal assembly via defective endonucleolytic cleavage. Anauxetic dysplasia mutations thus lead to poor processing of ribosomal RNA while allowing normal mRNA processing and, therefore, genetically separate the different functions of RNase MRP.     

HOXA10 and HOXA13 sequence variations in human female genital malformations including congenital absence of the uterus and vagina

Congenital genital malformations occurring in the female population are estimated to be 5 per 1000 and associate with infertility, abortion, stillbirth, preterm delivery and other organ abnormalities. Complete aplasia of the uterus, cervix and upper vagina (Mayer–Rokitansky–Küster–Hauser (MRKH) syndrome) has an incidence of 1 per 4000 female live births. The molecular etiology of congenital genital malformations including MRKH is unknown up to date. The homeobox (HOX) genes HOXA10 and HOXA13 are involved in the development of human genitalia. In this investigation, HOXA10 and HOXA13 genes of 20 patients with the MRKH syndrome, 7 non-MRKH patients with genital malformations and 53 control women were sequenced to assess for DNA variations. A total of 14 DNA sequence variations (10 novel and 4 known) within exonic and untranslated regions were detected in HOXA10 and HOXA13 among our cohorts. Four HOXA10 and two HOXA13 DNA sequence variations were found solely in patients with genital malformations. In addition to mutations resulting in synonymous amino acid substitutions, in the HOXA10 gene a missense mutation was identified and predicted by computer analysis as probably damaging to protein function in two non-MRKH patients, one with a bicornate and the other patient with a septated uterus. A novel exonic HOXA10 cytosine deletion was also identified in a non-MRKH patient with a septate uterus and renal malformations resulting in a premature stop codon and loss of the homeodomain helix 3/4. This cytosine deletion and the missense mutation in HOXA10 were analysed by real time PCR and sequencing, respectively, in two additional larger cohorts of 103 patients with MRKH and 109 non-MRKH patients with genital malformations. No other patients were found with the cytosine deletion however one additional patient was identified regarding the missense mutation. Rare DNA sequence variations in the HOXA10 gene could contribute to the misdevelopment of female internal genitalia.     

Comparative pollen morphology of annual Trigonella L. (Fabaceae) in Turkey

Pollen morphology of 38 Trigonella species was investigated with light microscopies and scanning electron microscopies. Pollen slides were prepared using Wodehouse technique. The pollen grains of Trigonella members are radially symmetrical and isopolar, their outlines are oblong in equatorial view and circular in polar view. Amb is semicircular. The pollen grains are prolate-spheroidal, oblate-spheroidal, suboblate, spheroidal, and prolate with the polar axes 13.5–49.9 μm and the equatorial axes 10.4–43.7 μm. The smallest dimensions are observed in T. spinosa and T. brachycarpa, and the largest in T. carica and T. rhytidocarpa. The pollen grains of Trigonella taxa are usually tricolporate or rarely tricolpate, pantocolporate, tetracolporate, and tricolpodiporate. Various ornamentation types were observed: Microreticulate (section Samaroideae, Pectinatae, Falcatulae, Cylindricae, Bucerates, Reflexae, Isthmocarpae, Capitatae and Foenum-graecum), rugulate-scabrate (section Lunatae, Uncinatae), perforate (T. halophila, T. rigida and T. carica from section Bucerates) and retipilatae (section Biebersteinianae) at equator region and psilate-perforate (section Samaroideae, Pectinatae, Bucerates, Reflexae, Isthmocarpae, Foenum-graecum, T. coelesyriaca, T. cilicica), rugulate-scabrate (section Lunatae, Uncinatae), microreticulate (Falcatulae, Cylindricae and Foenum-graecum) and retipilatae (section Biebersteinianae) at polar region. Ornamentations, pollen shape and the aperture type have been observed as important morphological characters.     

Biogenesis of cbb3-type cytochrome c oxidase in Rhodobacter capsulatus

The cbb₃-type cytochrome c oxidases (cbb₃-Cox) constitute the second most abundant cytochrome c oxidase (Cox) group after the mitochondrial-like aa₃-type Cox. They are present in bacteria only, and are considered to represent a primordial innovation in the domain of Eubacteria due to their phylogenetic distribution and their similarity to nitric oxide (NO) reductases. They are crucial for the onset of many anaerobic biological processes, such as anoxygenic photosynthesis or nitrogen fixation. In addition, they are prevalent in many pathogenic bacteria, and important for colonizing low oxygen tissues. Studies related to cbb₃-Cox provide a fascinating paradigm for the biogenesis of sophisticated oligomeric membrane proteins. Complex subunit maturation and assembly machineries, producing the c-type cytochromes and the binuclear heme b₃-Cu_B center, have to be coordinated precisely both temporally and spatially to yield a functional cbb₃-Cox enzyme. In this review we summarize our current knowledge on the structure, regulation and assembly of cbb₃-Cox, and provide a highly tentative model for cbb₃-Cox assembly and formation of its heme b₃-Cu_B binuclear center. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes.