Изучение видового разнообразия бактерий рода Bifidobacterium кишечной микрофлоры с использованием метода MALDI-TOF масс-спектрометрии

Background: The members of genus Bifidobacterium represent a significant part of intestinal microbiota in adults and predominate in infants. Species repertoire of the intestinal bifidobacteria is known to be subjected to major changes with age; however, many details of this process are still to be elucidated.Objective: Our aim was to study the diversity of intestinal bifidobacteria and changes of their qualitative and quantitative composition characteristics during the process of growing up using MALDI-TOF mass-spectrometric analysis of pure bacterial cultures.Methods: A cross-sectional study of bifidobacteria in the intestinal microbiota was performed in 93 healthy people of the ages from 1 month to 57 years. Strains were identified using Microflex LT MALDI-TOF MS, the confirmation was performed by 16S rRNA gene fragment sequencing.Results: 93% of isolated bifidobacterial strains were successfully identified using MALDI-TOF mass-spectrometry. At least two of the strains from each species were additionally identified by 16S rRNA gene fragment sequencing, in all of the cases the results were the same. It was shown that the total concentration of bifidobacteria decreases with age (p 0.001) as well as the frequency of isolation of Bifidobacterium bifidum (p =0.020) and Bifidobacterium breve (p 0.001), and the frequency of isolation of Bifidobacterium adolescentis, increases (p 0.001), representing the continuous process of transformation of microbiota.Conclusion: The method of MALDI-TOF mass spectrometry demonstrated the ability to perform rapid and reliable identification of bifidobacteria that allowed the study of changes in the quantitative and qualitative characteristics of human microbiota in the process of growing up.Представители рода Bifidobacterium представляют значительную часть микрофлоры кишечника взрослых людей и численно доминируют в микрофлоре младенцев. Известно, что видовой состав кишечных бифидобактерий подвергается сильным изменениям с возрастом, однако многие детали этого процесса остаются неясными.Цель исследования: изучить видовое разнообразие бифидобактерий кишечника и изменения их качественного и количественного состава в процессе взросления человека при помощи технологии MALDI-TOF масс-спектрометрического анализа белковых профилей чистых культур.Методы: кросс-секционное исследование разнообразия бифидобактерий в составе нормальной микрофлоры кишечника проведено у 93 человек в возрасте от 1 мес до 57 лет. Осуществляли выделе- ние чистых культур и их идентификацию на приборе Microflex LT MALDI-TOF MS (Bruker Daltonics, Германия), подтверждение реализовывали с использованием секвенирования фрагмента гена 16S рРНК.Результаты: с применением MALDI-TOF масс-спектрометрии было успешно идентифицировано 93% выделенных штаммов бифидобактерий. Минимум по 2 представителя от каждого из видов были дополнительно определены методом секвенирования фрагмента гена 16SрРНК; во всех случаях результаты методов совпали. Показано, что с возрастом происходит снижение общей концентрации бифидобактерий (p 0,001), уменьшается встречаемость видов Bifidobacterium bifidum (p =0,020) и Bifidobacterium breve (p 0,001), а встречаемость вида Bifidobacterium adolescentis увеличивается (p 0,001), отражая постепенные процессы перестройки микрофлоры.Заключение: метод MALDI-TOF масс-спектрометрии показал возможность быстрой и надежной идентификации бифидобактерий, позволившей провести исследование изменений количественных и качественных показателей микрофлоры человека в процессе взрослени

"Tomography" of the cluster structure of light nuclei via relativistic dissociation

These lecture notes present the capabilities of relativistic nuclear physics for the development of the physics of nuclear clusters. Nuclear track emulsion continues to be an effective technique for pilot studies that allows one, in particular, to study the cluster dissociation of a wide variety of light relativistic nuclei within a common approach. Despite the fact that the capabilities of the relativistic fragmentation for the study of nuclear clustering were recognized quite a long time ago, electronic experiments have not been able to come closer to an integrated analysis of ensembles of relativistic fragments. The continued pause in the investigation of the "fine" structure of relativistic fragmentation has led to resumption of regular exposures of nuclear emulsions in beams of light nuclei produced for the first time at the Nuclotron of the Joint Institute for Nuclear Research (JINR, Dubna). To date, an analysis of the peripheral interactions of relativistic isotopes of beryllium, boron, carbon and nitrogen, including radioactive ones, with nuclei of the emulsion composition, has been performed, which allows the clustering pattern to be presented for a whole family of light nuclei.Comment: ISBN 978-3-319-01076-2. 55 pages, 28 figure

Co-limitation towards lower latitudes shapes global forest diversity gradients

The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers