Search PubMed⌕ Search

Biomedical subjects

E B Lewis

Publications and source records attributed to E B Lewis.

32 records · Page 2Linked to original sources
PubMed1985

Regulation of the genes of the bithorax complex in Drosophila.

The BX-C is a set of master control genes that trans-regulate other genes and thereby control much of the segmentation pattern of the fly. The BX-C genes are themselves regulated in cis and trans. Three rules governing cis-regulation of BX-C are applicable over a region extending from Ubx to at least iab-7, a distance of nearly 300 kb on the DNA map: The colinearity (COL) rule: genes are colinear with respect to map location and order of expression along the body axis, the only exception thus far being pbx+; the cis-inactivation (CIN) rule: a mutant lesion in one gene tends to cis-inactivate the wild-type gene(s) immediately distally; and the cis-overexpression (COE) rule: certain mutant lesions in a given gene cause the next most proximal gene to overexpress one segment more anterior to the one in which the latter gene normally expresses. A model is proposed that attempts to account for these rules by invoking a special cis-regulatory entity (E) that diffuses more efficiently along the chromosome than between chromosomes.

Animals↗
PubMed1982

Control of body segment differentiation in Drosophila by the bithorax gene complex.

The bithorax complex is a gene cluster whose function is to regulate still other genes in such a way that each segment of the body commencing with the second thoracic segment and proceeding posteriorly, develops a unique pattern of structures. Numerous cis-regulatory regions have been identified within the complex and are believed to bind to repressor-like substances elaborated by the wild-type alleles of at least two major trans-regulatory genes, Polycomb and extra sex combs. The more proximal is a gene in the complex (with the exception of postbithorax) the more likely it is to be derepressed; the more posterior is a segment in the organism, the greater is the number of BX-C genes that become derepressed in that segment. A gradient in repressor substance(s) and a gradient in affinity of the cis-regulatory regions for repressor can account in a formal sense for the regulation of the BX-C genes themselves.

Animals↗
PubMed1978

A gene complex controlling segmentation in Drosophila.

The bithorax gene complex in Drosophila contains a minimum of eight genes that seem to code for substances controlling levels of thoracic and abdominal development. The state of repression of at least four of these genes is controlled by cis-regulatory elements and a separate locus (Polycomb) seems to code for a repressor of the complex. The wild-type and mutant segmentation patterns are consistent with an antero-posterior gradient in repressor concentration along the embryo and a proximo-distal gradient along the chromosome in the affinities for repressor of each gene's cis-regulatory element.

Abdomen↗
PubMed1977

Setting up in private practice. A guide for the newly appointed consultant.

If you are considering going into private practice under the present contract weigh up the cost, seek advice as to prospective earnings, join a partnership if you can, buy sound sensible equipment (second-hand if possible), insure for super-annuation and sickness benefits right away--it is both cheaper and safer. Agree a sensible NHS programme from the start using the advice of the BMA and the Association of Anaesthetists, and, when you are an established practitioner and a young colleague joins you, try to give him a helping hand and sound advice. The sine qua non of survival is co-operation.

Anesthesiology↗
PubMed1975

Possible genetic consequences of irradiation of tumors in childhood.

Dysgenic and radiation-induced types of genetic risks are evaluated for the progeny of persons who received childhood tumor therapy. The dysgenic risks may be quite high for certain types of tumors. The genetic defects of greatest concern following paternal irradiation are likely to be those caused by dominant mutations and unbalanced translocations, whereas chromosomal trisomies may be most important following maternal irradiation. Ways of alleviating these risks are discussed.

Child↗