Wannier interpolation of the electron-phonon matrix elements in polar semiconductors: Polar-optical coupling in GaAs

We generalize the Wannier interpolation of the electron-phonon matrix elements to the case of polar-optical coupling in polar semiconductors. We verify our methodological developments against experiments, by calculating the widths of the electronic bands due to electron-phonon scattering in GaAs, the prototype polar semiconductor. The calculated widths are then used to estimate the broadenings of excitons at critical points in GaAs and the electron-phonon relaxation times of hot electrons. Our findings are in good agreement with available experimental data. Finally, we demonstrate that while the Fr\"ohlich interaction is the dominant scattering process for electrons/holes close to the valley minima, in agreement with low-field transport results, at higher energies, the intervalley scattering dominates the relaxation dynamics of hot electrons or holes. The capability of interpolating the polar-optical coupling opens new perspectives in the calculation of optical absorption and transport properties in semiconductors and thermoelectrics.Comment: To appear on Phys. Rev.

Study of association between polymorphisms in the PSMB5 (rs11543947) and PSMA3 (rs2348071) genes and multiple sclerosis in Latvians

Functional realization of many signalling proteins and transcription factors implicated in the development and progression of multiple sclerosis is mediated by proteasomes. Aim of this case-control study was to evaluate genetic variations in the PSMB5 and PSMA3 genes encoding proteasomal subunits on the susceptibility to multiple sclerosis in Latvians. Methods. The rs11543947 (PSMB5) and rs2348071 (PSMA3) loci were genotyped in 291 multiple sclerosis patients and 305 healthy individuals and analysed general, subtype and sex-specific associations with the disease. Results. Loci rs11543947 and rs2348071 were identified as disease neutral and susceptible respectively. The rs2348071 heterozygous genotype GA showed strong main effect (P < 0.001; OR = 1.891, 95 % CI [1.360–2.628]), and moderate (P < 0.01; OR = 1.663, 95 % CI [1.152– 2.402]) and strong (P < 0.001; OR = 2.459, 95 % CI [1.534–3.943]) association with relapsing-remitting and secondary progressive phases of disease respectively. No genotype-sex interaction associated with multiple sclerosis has been detected. Conclusions. Our results suggest susceptibility of the rs2348071 heterozygous genotype to multiple sclerosis in Latvians.Протеасоми опосередковують виконання функцій багатьох сигнальних білків і факторів транскрипції, залучених до розвитку розсіяного склерозу. Мета. Оцінити можливу асоціацію генетичних варіантів генів PSMB5 і PSMA3 зі схильністю до захворювання на розсіяний склероз з-поміж жителів Латвії. Meтоди. Локуси rs11543947 (PSMB5) і rs2348071 (PSMA3) генотипували у 291 хворого на розсіяний склероз та у 305 здорових індивідів і оцінювали за асоціацією із захворюваністю на розсіяний склероз як такий, із підтипами хвороби і пов’язаною зі статтю асоціацією. Результати. Локус rs11543947виявився не пов’язаним з хворобою, а локус rs2348071 – асоційованим з нею. Гетерозиготний генотип ГА локуса rs2348071 тісно асоційований із захворюванням як таким (P < 0,001; співвідношення шансів (СШ) = 1,891; 95 % ДІ [1.360–2.628]), помірно асоційований (P < 0,01; СШ = 1,663; 95 % ДІ [1,152–2,402]) з ремітуючо-рецидивуючою формою захворювання та сильно (P < 0,001; СШ = 2,459; 95 % ДІ [1,534–3,943]) – зі вторинно прогресуючою формою. Пов’язаної з хворобою взаємодії між статтю і генотипом суб’єкта не відмічено. Висновки. Наші результати вказують на те, що жителі Латвії з гетерозиготним генотипом rs2348071 схильні до захворювання на розсіяний склероз.Протеасомы опосредуют выполнение функций многих сигнальных белков и факторов транскрипции, вовлеченных в развитие рассеянного склероза. Цель. Оценить возможную ассоциацию генетических вариантов генов PSMB5 и PSMA3 с подверженностью заболеванию рассеянным склерозом среди жителей Латвии. Meтоды. Локусы rs11543947 (PSMB5) и rs2348071 (PSMA3) генотипировали у 291 больного рассеянным склерозом и у 305 здоровых индивидов и оценивали по ассоциации с заболеваемостью рассеянным склерозом как таковым, подтипами болезни и связанной с полом ассоциации. Результаты. Локус rs11543947 оказался не связанным с болезнью, а локус rs2348071 – ассоциированным с заболеванием. Гетерозиготный генотип ГА локуса rs2348071 тесно ассоциирован с заболеванием как таковым (P < 0,001; отношение шансов (ОШ) = 1,891, 95 % ДИ [1.360–2.628]), умеренно (P < 0,01; ОШ = 1,663, 95 % ДИ [1,152–2,402]) – с ремиттирующе-рецидивирующей формой заболевания и сильно (P < 0,001; ОШ = 2,459, 95 % ДИ [1,534–3,943]) – со вторично прогрессирущей формой. Связанного с болезнью взаимодействия между полом и генотипом субъекта не отмечено. Выводы. Наши результаты указывают на подверженность жителей Латвии с гетерозиготным генотипом rs2348071 заболеваемости рассеянным склерозом

Association of Obesity with Proteasomal Gene Polymorphisms in Children

The aim of this study was to ascertain possible associations between childhood obesity, its anthropometric and clinical parameters, and three loci of proteasomal genes rs2277460 (PSMA6 c.-110C>A), rs1048990 (PSMA6 c.-8C>G), and rs2348071 (PSMA3 c. 543+138G>A) implicated in obesity-related diseases. Obese subjects included 94 otherwise healthy children in Latvia. Loci were genotyped and then analyzed using polymerase chain reactions, with results compared to those of 191 nonobese controls. PSMA3 SNP frequency differences between obese children and controls, while not reaching significance, suggested a trend. These differences, however, proved highly significant (PG SNP differences, while being nonsignificant, likewise suggested a trend in comparison to the nonobese controls. No PSMA6 c.-110C>A SNP differences were detected in the obese group or its subsets. Finally, PSMA3 SNP differences were significantly associated (P<0.05) with circulating low-density lipoprotein cholesterol (LDL) levels. Our results clearly implicate the PSMA3 gene locus as an obesity risk factor in those Latvian children with a family history of obesity. While being speculative, the clinical results are suggestive of altered circulatory LDL levels playing a possible role in the etiology of obesity in the young

Genetic differentiation and geographical Relationship of Asian barley landraces using SSRs

Genetic diversity in 403 morphologically distinct landraces of barley (Hordeum vulgare L. subsp. vulgare) originating from seven geographical zones of Asia was studied using simple sequence repeat (SSR) markers from regions of medium to high recombination in the barley genome. The seven polymorphic SSR markers representing each of the chromosomes chosen for the study revealed a high level of allelic diversity among the landraces. Genetic richness was highest in those from India, followed by Pakistan while it was lowest for Uzbekistan and Turkmenistan. Out of the 50 alleles detected, 15 were unique to a geographic region. Genetic diversity was highest for landraces from Pakistan (0.70 ± 0.06) and lowest for those from Uzbekistan (0.18 ± 0.17). Likewise, polymorphic information content (PIC) was highest for Pakistan (0.67 ± 0.06) and lowest for Uzbekistan (0.15 ± 0.17). Diversity among groups was 40% compared to 60% within groups. Principal component analysis clustered the barley landraces into three groups to predict their domestication patterns. In total 51.58% of the variation was explained by the first two principal components of the barley germplasm. Pakistan landraces were clustered separately from those of India, Iran, Nepal and Iraq, whereas those from Turkmenistan and Uzbekistan were clustered together into a separate group

Many-body calculations of plasmon and phonon satellites in angle-resolved photoelectron spectra using the cumulant expansion approach

The interaction of electrons with crystal lattice vibrations (phonons) and collective charge-density fluctuations (plasmons) influences profoundly the spectral properties of solids revealed by photoemission spectroscopy experiments. Photoemission satellites, for instance, are a prototypical example of quantum emergent behavior that may result from the strong coupling of electronic states to plasmons and phonons. The existence of these spectral features has been verified over energy scales spanning several orders of magnitude (from 50 meV to 15-20 eV) and for a broad class of compounds such as simple metals, semiconductors, and highly-doped oxides. During the past few years the cumulant expansion approach, alongside with the GW approximation and the theory of electron-phonon and electron-plasmon coupling in solids, has evolved into a predictive and quantitatively accurate approach for the description of the spectral signatures of electron-boson coupling entirely from first principles, and it has thus become the state-of-the-art theoretical tool for the description of these phenomena. In this chapter we introduce the fundamental concepts needed to interpret plasmon and phonon satellites in photoelectron spectra, and we review recent progress on first-principles calculations of these features using the cumulant expansion method

Matrin 3 is a co-factor for HIV-1 Rev in regulating post-transcriptional viral gene expression

Post-transcriptional regulation of HIV-1 gene expression is mediated by interactions between viral transcripts and viral/cellular proteins. For HIV-1, post-transcriptional nuclear control allows for the export of intron-containing RNAs which are normally retained in the nucleus. Specific signals on the viral RNAs, such as instability sequences (INS) and Rev responsive element (RRE), are binding sites for viral and cellular factors that serve to regulate RNA-export. The HIV-1 encoded viral Rev protein binds to the RRE found on unspliced and incompletely spliced viral RNAs. Binding by Rev directs the export of these RNAs from the nucleus to the cytoplasm. Previously, Rev co-factors have been found to include cellular factors such as CRM1, DDX3, PIMT and others. In this work, the nuclear matrix protein Matrin 3 is shown to bind Rev/RRE-containing viral RNA. This binding interaction stabilizes unspliced and partially spliced HIV-1 transcripts leading to increased cytoplasmic expression of these viral RNAs

Positive Regulation of DNA Double Strand Break Repair Activity during Differentiation of Long Life Span Cells: The Example of Adipogenesis

Little information is available on the ability of terminally differentiated cells to efficiently repair DNA double strand breaks (DSBs), and one might reasonably speculate that efficient DNA repair of these threatening DNA lesions, is needed in cells of long life span with no or limited regeneration from precursor. Few tissues are available besides neurons that allow the study of DNA DSBs repair activity in very long-lived cells. Adipocytes represent a suitable model since it is generally admitted that there is a very slow turnover of adipocytes in adult. Using both Pulse Field Gel Electrophoresis (PFGE) and the disappearance of the phosphorylated form of the histone variant H2AX, we demonstrated that the ability to repair DSBs is increased during adipocyte differentiation using the murine pre-adipocyte cell line, 3T3F442A. In mammalian cells, DSBs are mainly repaired by the non-homologous end-joining pathway (NHEJ) that relies on the DNA dependent protein kinase (DNA-PK) activity. During the first 24 h following the commitment into adipogenesis, we show an increase in the expression and activity of the catalytic sub-unit of the DNA-PK complex, DNA-PKcs. The increased in DNA DSBs repair activity observed in adipocytes was due to the increase in DNA-PK activity as shown by the use of DNA-PK inhibitor or sub-clones of 3T3F442A deficient in DNA-PKcs using long term RNA interference. Interestingly, the up-regulation of DNA-PK does not regulate the differentiation program itself. Finally, similar positive regulation of DNA-PKcs expression and activity was observed during differentiation of primary culture of pre-adipocytes isolated from human sub-cutaneous adipose tissue