Protamine-Cre recombinase transgenes efficiently recombine target sequences in the male germ line of mice, but not in embryonic stem cells

The production of subtle or conditional mutations in mice through the combined use of site-specific and homologous recombination has become an increasingly widespread experimental paradigm in mammalian genetics. Embryonic stem cells containing recombinase transgenes that were expressed in the male germ line, but not in other tissues or in the embryonic stem cells themselves, would substantially simplify the production of such alleles. Here we show that transgenes comprised of the mouse protamine 1 promoter and the Cre recombinase coding sequence mediate the efficient recombination of a Cre target transgene in the male germ line, but not in other tissues. Embryonic stem cell lines generated from one of these transgenic strains were transfected with targeting vectors that included loxP-flanked selectable markers, and homologously recombined alleles containing the marker and functional loxP sites were isolated. These results establish the potential of the system for substantially reducing the time, effort, and resources required to produce homologously recombined alleles in mice that have been secondarily rearranged by a site-specific recombinase.     

Wear Resistance of 30KhGSA Steel Under the Conditions of Rolling with Sliding

Materials Science - We study the regularities of changes in the wear resistance of triboelements made of 30KhGSA steel under extreme conditions of friction depending on the friction moment,...     

Effect of Textured Dentated Surfaces on 30KhGSA Steel Damage and Life at Fatigue,Fretting Fatigue,and Fretting

Strength of Materials - Machines and constructions are noted to contain components, units, and assemblies, which are joined together, forming a large number of contacting pairs. At operating loads,...     

Exact bounds on failure probability in the “strength-load” model with incomplete information

The infimum and supremum of failure probability (i. e., the probability that the load exceeds the strength) are obtained under the following assumptions: (a) one of the variables is Erlang distributed and the other has known mean and variance; (b) the distribution functions of both random variables are unknown and only the means and the upper bound of one of the distributions are known.Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 56–63, September–October, 1992.     

An Increase in the Refractive Index of a Multicomponent Silicate Glass by Six-Hundredths upon the Na+glass–Li+meltIon Exchange

An increase in the refractive index of the glass surface by n= 0.06 after the Na⁺ _glass–Li⁺ _meltion exchange is obtained for the first time.     

Press-moldcases made from centrifugally cast wear-resistant alloys

Conclusions The cases of press-molds having large linear dimensions and thin walls can be obtained from centrifugally cast high-chromium cast iron with subsequent hardening at 1080–1100°C in oil. The resistance of the experimental cases when first placed in the mold is three times greater than in ordinary cases made of 20Kh steel. The regrinding of the cases within the tolerance limits for refractory products, specified by GOST 5500-75, and subsequent operation without additional heat treatment, makes it possible to boost their overall resistance.Translated from Ogneupory, No. 1, pp. 21–23, January, 1981.