Regulation of lipogenesis in vivo by glucose availability and insulin secretion in maternal and foetal tissues during late gestation in the rat. Effect of glucose intubation, streptozotocin-induced diabetes and starvation.

Administration of an oral load of glucose did not change the rate of lipogenesis in maternal liver during late gestation. However, streptozotocin-induced diabetes or starvation decreased maternal liver lipogenesis at 20-22 days of gestation. Glucose intubation, on the other hand, increased foetal lipogenesis at 21-22 days. In addition, maternal starvation decreased foetal lipogenesis and plasma insulin concentration. However, chronic hyperglycaemia induced by streptozotocin administration to the mother did not change foetal liver lipogenesis.     

Phytochrome in etiolated annual rye

Summary During a seven-fold increase in length the content of the coleoptile in photoreversible phytochrome increased four-fold and that of the primary leaf nine-fold. The phytochrome content, during growth, expressed on a fresh- or dry-weight basis did not vary greatly for either organ. Phytochrome per mg dry weight (OD⁷³⁰/mg=0.5) was nearly the same in the leaf as in the coleoptile. Coleoptiles studied had a constant DNA content of 4.1 g per organ. DNA content of the leaf increased with age. Phytochrome per DNA was much higher in the coleoptile than in the primary leaf and increased with growth in each of these organs. Thus, there was not a constant amount of phytochrome per cell in either tissue with increasing age and there was not the same amount of phytochrome per cell in the coleoptile as in the primary leaf at any age.This work was supported in part by U.S. Atomic Energy Commission Contract No. AT (30-I)2373.     

SDSE: A software package to simulate the evolution of a pair of DNA sequences

An algorithm to simulate DNA sequence evolution under a generalstochastic model, including as particular cases all the previouslyused schemes of nucleotide substitution, is described. The simulationis carried out on finite, variable length, DNA sequences througha strict stochastic process, according to the particular substitutionrates imposed by each scheme. Five FORTRAN programs, runningon an IBM PC and compatibles, carry out all the tasks neededfor the simulation. They are menu driven and interfaced to thesystem through a principal menu. All sequence data files usedand generated by the SDSE package conform to the standard GenBankdatabase format, thus allowing the use of any sequence retrievedfrom this databank, as well as the application of other packagesto analyse, manipulate or retrieve simulated sequences. Received on August 23, 1988; accepted on November 15, 1988     

A 14-kilodalton selenium-binding protein in mouse liver is fatty acid-binding protein

In a previous study, we purified three selenium-binding proteins (molecular masses 56, 14, and 12 kDa) from mouse liver using column chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The aim of the present study was to determine the amino acid sequence of the 14-kDa protein thereby establishing any relationship with known proteins. Although the amino terminus of the 14-kDa protein was blocked, separate in situ digestions of the protein with endoproteinases Glu-c and Lys-c gave overlapping peptides that provided a continuous sequence of 93 amino acids. This sequence exhibited a 92.5% sequence homology with rat liver fatty acid-binding protein. In situ enzymatic digestion and partial sequencing of a 12-kDa selenium-binding protein revealed identical homology to the 14-kDa protein. The 14-kDa protein bound specifically to an oleate-affinity column from which the protein and 75Se coeluted. Delipidation or sodium dodecyl sulfate treatment failed to remove 75Se from the protein, indicating that the selenium moiety was tightly bound to the protein. These observations confirm that the mouse liver selenium-binding 14-kDa protein is a fatty acid-binding protein. The nature of the selenium linkage to the protein still needs to be explored.     

In search of mammary gland stem cells

Summary The evidence for mammary epithelial stem cells and their phenotypic characteristics in normal and neoplastic development is reviewed. The presence of stem cells in all parts of the mammary parenchyma at all stages of differentiation has been demonstrated by transplantation experiments. The phenotypic characterization of stem cells has been defined by a battery of monospecific antibodies. These studies suggest that a mammary epithelium stem cell compartment exists in the basal layer of the gland as well as in the end bud. Whether these same stem cells are expressed in mammary preneoplasias and neoplasias has not been answered conclusively. Phenotypic markers specific for stem cells and stably expressed in transformed cell populations are needed to follow the fate of stem cells.Dedicated to Professor Stuart Patton on the occassion of his 70th birthday.