Unique sequences are interspersed among tandemly repeated elements in the murine gamma 1 switch segment.

Early in its differentiative pathway, a given B lymphocyte expresses immunoglobulin of the mu heavy chain class (IgM). Subsequent differentiative processes may involve rearrangement within the immunoglobulin heavy chain chromosomal locus to enable cells of the same lineage to synthesize immunoglobulins of other heavy chain classes (e. g. IgG, IgE or IgA), but with specificity for the same antigen as the original IgM molecule. Switch recombination, the molecular event which facilitates this chromosomal rearrangement, has been shown to occur between segments of DNA consisting of tandemly repeated unit sequences. These DNA segments have been functionally defined as switch regions. We have cloned the gamma 1 switch region from the BALB/c germline, and have demonstrated that significantly divergent sequence elements are interspersed among the tandemly repeated units characteristic of this switch region. We show that these unique elements exist in at least three copies within the switch segment, and discuss the implications of this novel and previously unreported primary structure.     

A mass mortality of fishes caused by receding water levels in the vegetated littoral zone of the West Kleinemonde Estuary,South Africa

On 15 November 2017 the mouth of the West Kleinemonde Estuary breached following heavy catchment rains and increased river flow. The water level in the estuary following mouth opening decreased by 1.65 m within 24 h, resulting in an almost complete draining of the littoral zone where large beds of the aquatic macrophyte Ruppia cirrhosa and mats of the associated filamentous algae were present. As the water depth within the plant beds decreased, the macrophytes, together with the algal filaments, created an increasingly dense mat, trapping fish that were resident, foraging or passing through the littoral zone. By 16 November 2017 large numbers of fishes belonging to at least 20 species were trapped in pools and depressions within the littoral, as well as within the R. cirrhosa beds and filamentous algal mats in the lower reaches of this system. Other affected taxa included crustaceans, especially isopods, and large numbers of small bivalves attached to macrophyte vegetation. Beneficiaries of the fish kill, in terms of unexpected food availability, included a variety of piscivorous bird species and the Cape clawless otter Aonyx capensis. This is the first documented account of a diverse species fish kill associated with estuary mouth breaching.     

CD14 C-159T and early infection with Pseudomonas aeruginosa in children with cystic fibrosis

Early acquisition of Pseudomonas aeruginosa is associated with a poorer prognosis in patients with cystic fibrosis. We investigated whether polymorphisms in CD14, the lipopolysaccharide receptor, increase the risk of early infection. Forty-five children with cystic fibrosis were investigated with annual bronchoalveolar lavage (BAL) and plasma sCD14 levels. Plasma sCD14 levels were significantly lower in children from whom P.aeruginosa was subsequently isolated (492.75 μg/ml vs. 1339.43 μg/ml, p = 0.018). Those with the CD14 -159CC genotype had a significantly increased risk of early infection with P.aeruginosa suggesting that CD14 C-159T plays a role in determining the risk of early infection with P.aeruginosa.     

Myotone Dystrophien – und ihre Differenzialdiagnosen

The classic myotonic dystrophy, Steinert’s disease (DM1) was first described in 1909, and the second type, Ricker’s disease (DM2), in 1994. In 1992 the disease-causing mutation in DM1 was identified as a CTG repeat in the DMPK gene on chromosome 19q, and in 2001 the DM2 mutation was identified as a CCTG repeat expansion in the ZNF9 gene on chromosome 3q. Multisystemic symptoms of the diseases affect skeletal muscle, brain, eye, heart, and the endocrine system. The pathogenesis of both forms seems to be based on a gain-of-function RNA mechanism and on alterations in RNA metabolism and spliceopathy. Our review focuses on clinical features, diagnostic techniques, and new aspects of molecular pathogenesis and therapy.     

Das Marfan-Syndrom und verwandte monogene Krankheiten der Aorta

Marfan syndrome (MFS) is an autosomal dominant, pleiotropic disease of the connective tissue with a prevalence of about 1 in 5000 persons. MFS is characterized by manifestations in the cardiovascular system, eye, skeleton, lung, skin, and dura mater that show a high degree of intra- and interfamilial variability. Many manifestations develop during or shortly before puberty; severe complications rarely occur before adulthood. Many patients with MFS display a so-called marfanoid habitus with tall stature, dolichostenomelia (long, narrow extremities), dolichocephaly (disproportionately long and narrow head), as well as other skeletal abnormalities such as scoliosis and pes planus. Scoliosis occurs in approximately 60% of those affected, pectus deformities in up to two thirds. Ectopia lentis is seen in many patients with MFS and is almost always bilateral. MFS is characterized by a high risk for complications such as severe scoliosis or pectus deformities, spontaneous pneumothorax, retinal detachment, or glaucoma secondary to lens luxation. The most severe complications occur in the cardiovascular system, including in particular acute dissection of the ascending aorta, which generally follows a long period of progressive aortic dilatation. Before the introduction of modern treatment modalities, the average life expectancy of persons with MFS was estimated to be 32 years. Today, with medical care in multidisciplinary centers, an average life expectancy of over 60 years can be achieved. This article offers a review of established and novel concepts for the diagnosis and treatment of MFS and other hereditary diseases of the aorta.     

Klinik und Genetik des familiären Darmkrebses

Familial clustering of colorectal cancer (CRC) and early disease onset are indicators of an inherited tumour syndrome. Monogenic dispositions account for 3–5% of all CRC cases and are subdivided into hereditary non-polyposis colorectal cancer (HNPCC/Lynch syndrome) and various gastrointestinal polyposis syndromes. Many of these syndromes are characterised by a broad spectrum of extracolonic tumours. Early detection and accurate classification are essential in providing effective surveillance and treatment. Initial diagnosis is based on endoscopic and histological findings as well as on the presence of extracolonic manifestations and family history. Molecular genetic examination is important for the differential diagnosis, evaluation of recurrence risk, and predictive testing of asymptomatic at risk individuals; it is performed according to largely standardised algorithms. Diagnostic difficulties are common among the hamartomatous polyposes due to their broad phenotypic overlap and frequent uncertainties in histological evaluation, as well as among patients with few adenomas. Risk-adapted surveillance guidelines have been established for HNPCC and for the more frequently observed polyposis syndromes. Beyond established tumour syndromes, familial clustering of CRC (which is often of late onset) or the occurrence of few adenomas is likely to be based upon a multifactorial (complex) etiology. Although identification of the underlying genetic risk factors and biological pathways is still in the early stages, rapid progress is being made due to methodical developments such as genome-wide association studies and CNV analysis.     

Botanische Gärten in der Zeit des Kolonialismus. Auf der Jagd nach dem “Grünen Gold”

Plant Transfer and Botanical Gardens in Colonial Times A constant of economic history is the need of natural resources – in the past often of vegetable origin and available only from the countries of natural distribution. These countries often tried to protect their interests against the traders or users by declaring monopoles. Between these both poles botanic gardens acted very successfully and by far not according to modern ethic standards. Results of their activities were the transcontinental movements of plants and the initiation of new agricultural based industries. These should be exemplified by the British botanical gardens and species as tea shrub, rubber tree, and cinchona tree.     

Mosaike bei monogenen Erkrankungen

Mosaicism is defined as the simultaneous presence of cells with different genotypes that originate from a common zygote. Mutations can either be present in germline or somatic cells. Monogenic disorders apparently caused by a de novo mutation may show a recurrence risk due to germline mosaicism in a parent. Duchenne muscular dystrophy is a well investigated example with a high frequency of germline mosaicism and the estimation for the risk of recurrence is based on theoretical models and empirical data. Recently, somatic mutations have been uncovered in various syndromic disorders, such as Proteus syndrome or hemimegalencephaly and respective mutations often show gain-of-function properties. Genetic testing is mainly based on next generation sequencing technologies but still remains challenging; however, detection of somatic mosaicism is expected to be of increasing relevance in the diagnosis of monogenic disorders. Somatic mosaicism may also play a hitherto underestimated role in common disorders.