ТЕКТОНОТЕРМАЛЬНАЯ ЭВОЛЮЦИЯ ЗАГАНСКОГО КОМПЛЕКСА МЕТАМОРФИЧЕСКОГО ЯДРА ЗАБАЙКАЛЬЯ: РЕЗУЛЬТАТ ПОСТКОЛЛИЗИОННОГО РАЗРУШЕНИЯ МОНГОЛО-ОХОТСКОГО ОРОГЕНА В МЕЛУ – ПАЛЕОЦЕНЕ

Thermochronological reconstructions of the Zagan metamorphic core complex were carried out using samples from the central part of the core, mylonite zone detachment and lower nappe with U/Pb zircon dating, 40Ar/39Ar amphibole and mica dating, and apatite fission-track dating. In the tectonothermal evolution of the metamorphic core, there was distinguished an active phase (tectonic denudation) of the dome structure formation during the Early Cretaceous (131–114 Ma), which continued in the Late Cretaceous – Paleocene (111–54 Ma) in passive phase (erosive denudation). During an active phase, there was initiated a large-amplitude gently dipping normal fault (detachment), which was accompanied by tilting (sliding of rocks along subparallel listric faults). As a result, about 7 km thick rock strata underwent denudation over 17 Ma at a rate of about 0.4 mm/year. In passive phase, about 6 km thick rock strata were eroded over 57 Ma, with a denudation rate of about 0.1 mm/year. Thus, the Zagan metamorphic core complex was tectonically exposed from the mid-crust to depths of about 9 km in the Early Cretaceous as a result of post-collisional collapse of the Mongol-Okhotsk orogen. Further cooling of the rocks in the metamorphic core to depths of about 3 km occurred in the Late Cretaceous – Pliocene as a result of destruction of more than 6 km high mountains.Термохронологические реконструкции Заганского комплекса метаморфического ядра проводились по образцам центральной части ядра, зоны милонитов из детачмента и нижней части покрова с использованием U/Pb датирования циркона, 40Ar/39Ar датирования амфибола и слюд, трекового датирования апатита. В тектонотермальной эволюции метаморфического ядра выделена активная фаза (тектоническая денудация) в период раннего мела (131–114 млн лет), которая продолжилась в позднем мелу – палеоцене (111–54 млн лет) пассивной фазой (эрозионная денудация). В активную фазу произошла инициация крупноамплитудного пологопадающего сброса (детачмента), которая сопровождалась сползанием пород по субпараллельным листрическим сбросам. В результате за 17 млн лет было денудировано около 7 км мощности пород со скоростью около 0.4 мм/год. В пассивную фазу за 57 млн лет было размыто около около 6 км со скоростью денудации около 0.1 мм/год. Таким образом, тектоническая экспозиция Заганского метаморфического ядра со средних уровней коры до глубин около 9 км осуществлялась в раннем мелу в результате постколлизионного растяжения Монголо-Охотского орогена. Дальнейшее охлаждение пород метаморфического ядра до глубины около 3 км происходило в позднем мелу – плиоцене в результате разрушения горного поднятия, имеющего высоту более 6 км

High frequency of BRCA1, but not CHEK2 or NBS1 (NBN), founder mutations in Russian ovarian cancer patients

<p>Abstract</p> <p>Background</p> <p>A significant portion of ovarian cancer (OC) cases is caused by germ-line mutations in BRCA1 or BRCA2 genes. BRCA testing is cheap in populations with founder effect and therefore recommended for all patients with OC diagnosis. Recurrent mutations constitute the vast majority of BRCA defects in Russia, however their impact in OC morbidity has not been yet systematically studied. Furthermore, Russian population is characterized by a relatively high frequency of CHEK2 and NBS1 (NBN) heterozygotes, but it remains unclear whether these two genes contribute to the OC risk.</p> <p>Methods</p> <p>The study included 354 OC patients from 2 distinct, geographically remote regions (290 from North-Western Russia (St.-Petersburg) and 64 from the south of the country (Krasnodar)). DNA samples were tested by allele-specific PCR for the presence of 8 founder mutations (BRCA1 5382insC, BRCA1 4153delA, BRCA1 185delAG, BRCA1 300T>G, BRCA2 6174delT, CHEK2 1100delC, CHEK2 IVS2+1G>A, NBS1 657del5). In addition, literature data on the occurrence of BRCA1, BRCA2, CHEK2 and NBS1 mutations in non-selected ovarian cancer patients were reviewed.</p> <p>Results</p> <p>BRCA1 5382insC allele was detected in 28/290 (9.7%) OC cases from the North-West and 11/64 (17.2%) OC patients from the South of Russia. In addition, 4 BRCA1 185delAG, 2 BRCA1 4153delA, 1 BRCA2 6174delT, 2 CHEK2 1100delC and 1 NBS1 657del5 mutation were detected. 1 patient from Krasnodar was heterozygous for both BRCA1 5382insC and NBS1 657del5 variants.</p> <p>Conclusion</p> <p>Founder BRCA1 mutations, especially BRCA1 5382insC variant, are responsible for substantial share of OC morbidity in Russia, therefore DNA testing has to be considered for every OC patient of Russian origin. Taken together with literature data, this study does not support the contribution of CHEK2 in OC risk, while the role of NBS1 heterozygosity may require further clarification.</p

Charge exchange of a polar molecule at its cation

The Landau-Herring method is used to derive an analytic expression for the one-electron exchange interaction of a polar molecule with its positively charged ion, induced by a electron. Analogously to the classical Van der Pole method, the exchange interaction potential is averaged over the rotational states of colliding particlesyesBelgorod State Universit

Charge exchange of a polar molecule at its cation

yesThe Landau-Herring method is used to derive an analytic expression for the one-electron exchange interaction of a polar molecule with its positively charged ion, induced by a electron. Analogously to the classical Van der Pole method, the exchange interaction potential is averaged over the rotational states of colliding particlesBelgorod State Universit