Search PubMed⌕ Search

Biomedical subjects

E Selsing

Publications and source records attributed to E Selsing.

45 records · Page 3Linked to original sources
PubMed1976

Conformations of A,T-rich DNAs.

DNAs from the genomes of Clostridium perfringens and Cytophaga johnsonii display orthodox A-DNA and B-DNA structures despite their high (A+L) nucleotide content. Unique structures, such as those found for synthetic DNAs having specific special sequences, do therefore not necessarily occur for DNAs having more random base sequence even if these have unusual base compositions. Clostridium perfringens DNA exhibits unusual structural properties only prior to purification by gel filtration.

Adenine↗
PubMed1976

Conformations of satellite DNAs.

X-ray fiber diffraction studies of satellite DNAs from Gecarcinus lateralis, Drosophila virilis and Mus musculus, all of which have highly repetitious base sequences but with different degrees of sequence complexity, reveal only classical polynucleotide duplex structures in contrast to some highly repetitious synthetic DNAs.

Animals↗
PubMed1976

Models of triple-stranded polynucleotides with optimised stereochemistry.

Detailed models are presented for the triple-stranded polynucleotide helices of poly (U)-poly (A)-poly (U) (two forms), poly (U)-poly d (A) -poly (U), poly d(C)-poly d(I)-poly d(C), poly d(T)-polyd(A)-poly d(T) and poly (I)-poly (A)-poly (I). The models were genrated using a computerized, linked-atom procedure which preserves standard bond lengths, bond anglesand sugar ring conformations, constrains the helices to have the pitches and symmetries observed in X-ray diffraction experiments, and optimises the non-bonded interatomic contacts including hydrogen bonds. The possible biological sigificance of such complexes is discussed.

Computers↗
PubMedDate not supplied

Novel kappa light-chain gene rearrangements in mouse lambda light chain-producing B lymphocytes.

The genes that encode the immunoglobulin proteins made by B lymphocytes are made up of segments that are separately encoded in the germ-line genome and brought together by recombination during B-cell ontogeny. There are two types of immunoglobulin light chain, kappa and lambda, but only a single type is expressed in individual B cells. It is thought that kappa gene recombination precedes lambda gene recombination during B-cell ontogeny. We describe here unusual recombinations that have occurred in two lambda-producing B-cell lines and suggest that they are involved in the developmental switch from kappa to lambda gene expression in maturing B cells. These recombinations involve the J kappa-C kappa introns of V-J joined but nonfunctional kappa genes and a sequence that in the germ line occurs downstream of the C kappa exon (called RS, for recombining sequence).

B-Lymphocytes↗
PubMedDate not supplied

Recombination between immunoglobulin variable region gene segments is enhanced by transcription.

Immunoglobulin (Ig) variable (V) region genes are assembled in precursor B (pre-B) lymphocytes from multiple germline segments. The heavy-chain V-region gene is composed of variable (VH), diversity (D) and joining (JH) segments; kappa (K) and lambda (lambda) light-chain V-region genes have analogous VL and JL segments. Assembly of Ig V-gene segments, as well as those of the highly related T-cell receptor, is regulated at several levels and shows both stage and tissue specificity; for example Ig heavy-chain V-gene assembly precedes that of Ig light chains during B-cell differentiation. Joining of all classes of V-gene segments involves conserved recognition sequences that are probably targets for a common recombinase. Evidence has been presented suggesting that rearrangement of specific classes of segments is regulated by modulation of their accessibility to the recombinase. To elucidate mechanisms which control V-region gene assembly, we have investigated the effect of flanking gene expression on the frequency at which introduced V-gene segments are assembled in pre-B cell lines. Our findings suggest that transcription may play a direct role in the regulation of immunoglobulin V-gene assembly.

Animals↗