No abstract

African mole-rats (Bathyergidae, Rodentia) of the (eu)social genus Fukomys are one of the most speciose mammal genera endemic to Sub-Saharan Africa. Fukomys distributed in the Zambezian phytochorion is characterized by extreme chromosomal variation (2n = 40-78). We inferred a molecular phylogeny of Zambezian Fukomys to resolve the interrelationships and the evolutionary history of the known chromosomal races. We sequenced the entire cytochrome b gene (1140 bp) for a total of 66 specimens representing 18 karyotypical races from Zambia. An additional 31 sequences were retrieved from GenBank including data on all other chromosomal races. The haplotypes belonging to a small chromosomal race from Salujinga cluster with the Fukomys mechowii (Giant mole-rat) haplotypes. Differential degrees of chromosomal variation are observed among the major mole-rat clades, which is most pertinent when comparing the central Zambezian Fukomys micklemi and the northern Zambezian Fukomys whytei clades. The karyotypically hyper-diverse (12 known chromosomal races) Fukomys micklemi clade shows low levels of cytochrome b sequence divergence. Within the F. whytei clade we find a more conservative pattern of chromosomal diversification (three known chromosomal races) while the levels of sequence divergence are much higher then in the F. micklemi clade. Our results suggest that chromosomal changes may drive phyletic divergence and, eventually, speciation. The observed cladogenetic events during the Plio-Pleistocene within the F. mechowii, F. whytei, F. damarensis and F. micklemi clades appear to coincide with climatically mediated speciation bursts in other savannah dwelling mammals, including hominids. Based on the molecular data presented, combined with morphological and chromosomal data, the taxonomic implication seems to be that Fukomys may contain several (undescribed) cryptic species.

Sucrose synthase (SuSy) catalyzes the reversible conversion of sucrose and a nucleoside diphosphate into fructose and nucleotide (NDP)-glucose. To date, only SuSy's from plants and cyanobacteria, both photosynthetic organisms, have been characterized. Here, four prokaryotic SuSy enzymes from the nonphotosynthetic organisms Nitrosomonas Europaea (SuSyNe), Acidithiobacillus caldus (SuSyAc), Denitrovibrio acetiphilus (SusyDa), and Melioribacter roseus (SuSyMr) were recombinantly expressed in Escherichia coli and thoroughly characterized. The purified enzymes were found to display high-temperature optima (up to 80 °C), high activities (up to 125 U/mg), and high thermostability (up to 15 min at 60 °C). Furthermore, SuSyAc, SuSyNe, and SuSyDa showed a clear preference for ADP as nucleotide, as opposed to plant SuSy's which prefer UDP. A structural and mutational analysis was performed to elucidate the difference in NDP preference between eukaryotic and prokaryotic SuSy's. Finally, the physiological relevance of this enzyme specificity is discussed in the context of metabolic pathways and genomic organization.

No abstract

Sjögren’s syndrome (SS) is a complex autoimmune rheumatic disease that specifically targets salivary and lachrymal glands. As such, patients typically had ocular and oral dryness and salivary gland swelling. Moreover, skin, nasal and vaginal dryness are frequently present. In addition to dryness, musculoskeletal pain and fatigue are the hallmarks of this disease and constitute the classic symptom triad presented by the vast majority of patients. Up to 30% to 50 % of patients with SS may present systemic disease; moreover, there is an increased risk for the development of non-Hodgkin’s lymphoma that occurs in a minority of patients. The present work was developed in the framework of the European Reference Network (ERN) dedicated to Rare and Complex Connective Tissue and Musculoskeletal Diseases (ReCONNET). In line with its goals of aiming to improve early diagnosis, treatment and care of rare connective and musculoskeletal diseases, ERN-ReCONNET set to review the current state of clinical practice guidelines (CPGs) in the rare and complex connective tissue diseases of interest of the network. Therefore, the present work was aimed at providing a state of the art of CPGs for SS.