Demonstration of in vivo engineered tandem duplications of varying sizes using CRISPR and recombinases in Drosophila melanogaster

Tandem gene duplicates are important parts of eukaryotic genome structure, yet the phenotypic effects of new tandem duplications are not well-understood, in part owing to a lack of techniques to build and modify them. We introduce a method, Recombinase-Mediated Tandem Duplication, to engineer specific tandem duplications in vivo using CRISPR and recombinases. We describe construction of four different tandem duplications of the Alcohol Dehydrogenase (Adh) gene in Drosophila melanogaster, with duplicated block sizes ranging from 4.2 to 20.7 kb. Flies with the Adh duplications show elevated ADH enzyme activity over unduplicated single copies. This approach to engineering duplications is combinatoric, opening the door to systematic study of the relationship between the structure of tandem duplications and their effects on expression.

Demonstration of in vivo engineered tandem duplications of varying sizes using CRISPR and recombinases in Drosophila melanogaster

Tandem gene duplicates are important parts of eukaryotic genome structure, yet the phenotypic effects of new tandem duplications are not well-understood, in part owing to a lack of techniques to build and modify them. We introduce a method, Recombinase-Mediated Tandem Duplication (RMTD), to engineer specific tandem duplications in vivo using CRISPR and recombinases. We describe construction of four different tandem duplications of the Alcohol Dehydrogenase ( Adh ) gene in Drosophila melanogaster , with duplicated block sizes ranging from 4.2 kb to 20.7 kb. Flies with the Adh duplications show elevated ADH enzyme activity over unduplicated single copies. This approach to engineering duplications is combinatoric, opening the door to systematic study of the relationship between the structure of tandem duplications and their effects on expression.

Zinc secretion in the oviduct of the coturnix quail

The oviduct from laying quail were used to investigate mechanisms of trace mineral secretion and the possible role of metallothionein in this process. Secretion of zinc occurred maximally at pH 5.4, which is close to the normal pH of the oviduct. Secretion occurred to a much greater extent in the isthmus and shell gland than in the magnum, the major protein-secretory section of the oviduct. Intraperitoneal administration of cadmium resulted in a marked reduction in Zn secretion from the oviduct of laying quail. This effect could not be correlated with metallothionein since metallothionein could not be detected in any section of the oviduct in control or Cd-induced quail. Small-molecular-weight metal-binding ligands were present in the isthmus and shell gland, which may play a role in trace mineral mobilization. Histological evaluation by light and elelctron microscopy show that Zn is transported from the smooth muscle cells through the connective tissue matrix in the extracellular space to the epithelial goblet cells. Presumably, Zn and other trace minerals are secreted from the secretory goblet cells into the egg.

Successful peritoneal dialysis in an infant weighing less than 800 grams

This paper describes the technical feasibility and successful outcome of peri toneal dialysis in the management of a 710-gram, 25-week-gestation infant.