Observation of three-component fermions in the topological semimetal molybdenum phosphide.

In quantum field theory, Lorentz invariance leads to three types of fermion-Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems. The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally, and that of Majorana fermions is supported by various experiments. However, in condensed-matter systems, fermions in crystals are constrained by the symmetries of the 230 crystal space groups rather than by Lorentz invariance, giving rise to the possibility of finding other types of fermionic excitation that have no counterparts in high-energy physics. Here we use angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac-Weyl-Majorana classification, which attributes Dirac and Weyl fermions to four- and two-fold degenerate points, respectively. We also observe pairs of Weyl points in the bulk electronic structure of the crystal that coexist with the three-component fermions. This material thus represents a platform for studying the interplay between different types of fermions. Our experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems.

Unconventional Transverse Transport above and below the Magnetic Transition Temperature in Weyl Semimetal EuCd_{2}As_{2}.

As exemplified by the growing interest in the quantum anomalous Hall effect, the research on topology as an organizing principle of quantum matter is greatly enriched from the interplay with magnetism. In this vein, we present a combined electrical and thermoelectrical transport study on the magnetic Weyl semimetal EuCd_{2}As_{2}. Unconventional contribution to the anomalous Hall and anomalous Nernst effects were observed both above and below the magnetic transition temperature of EuCd_{2}As_{2}, indicating the existence of significant Berry curvature. EuCd_{2}As_{2} represents a rare case in which this unconventional transverse transport emerges both above and below the magnetic transition temperature in the same material. The transport properties evolve with temperature and field in the antiferromagnetic phase in a different manner than in the paramagnetic phase, suggesting different mechanisms to their origin. Our results indicate EuCd_{2}As_{2} is a fertile playground for investigating the interplay between magnetism and topology, and potentially a plethora of topologically nontrivial phases rooted in this interplay.

Breast ductal carcinoma in situ with micro-invasion versus ductal carcinoma in situ: a comparative analysis of clinicopathological and mammographic findings.

AIM: To determine the differences in clinicopathological and mammographic findings between ductal carcinoma in situ (DCIS) and ductal carcinoma in situ with micro-invasion (DCIS-MI) and explore clinicopathological and mammographic factors associated with DCIS-MI. MATERIALS AND METHODS: All DCIS patients with or without micro-invasion who underwent preoperative mammography at The Affiliated Hospital of Qingdao University from January 2016 through June 2020 were identified retrospectively. The correlations of clinicopathological findings with DCIS-MI were evaluated using univariate and multivariate binary logistic regression analyses. Imaging findings were compared between the groups by using the Pearson chi-square test. RESULTS: A total of 445 DCIS lesions and 151 DCIS-MI lesions were included in the final analysis. Large extent (≥2.7 cm), high nuclear grade, comedo-type, negative progesterone receptor (PR), negative oestrogen receptor (ER), high Ki-67 and axillary lymph node metastasis were more frequently found in DCIS-MI than in DCIS (all p<0.05), and the first four of these were found to be independent predictors of DCIS-MI in the multivariate analysis (all p<0.05). Regarding imaging findings, compared to DCIS, DCIS-MI showed fewer occult lesions and more lesions with calcifications in mass, asymmetry, and architectural distortion (p=0.004). Grouped calcifications were usually associated with DCIS, while regional calcifications were commonly found in DCIS-MI (p<0.05). CONCLUSION: Large extent, high nuclear grade, comedo-type and negative PR were found to be independent predictors of DCIS-MI. Lesions with calcifications and regional calcifications were more likely associated with DCIS-MI on mammography.

Atomically Precise Lateral Modulation of a Two-Dimensional Electron Liquid in Anatase TiO2 Thin Films.

Engineering the electronic band structure of two-dimensional electron liquids (2DELs) confined at the surface or interface of transition metal oxides is key to unlocking their full potential. Here we describe a new approach to tailoring the electronic structure of an oxide surface 2DEL demonstrating the lateral modulation of electronic states with atomic scale precision on an unprecedented length scale comparable to the Fermi wavelength. To this end, we use pulsed laser deposition to grow anatase TiO2 films terminated by a (1 × 4) in-plane surface reconstruction. Employing photostimulated chemical surface doping we induce 2DELs with tunable carrier densities that are confined within a few TiO2 layers below the surface. Subsequent in situ angle-resolved photoemission experiments demonstrate that the (1 × 4) surface reconstruction provides a periodic lateral perturbation of the electron liquid. This causes strong backfolding of the electronic bands, opening of unidirectional gaps and a saddle point singularity in the density of states near the chemical potential.

Topologically Entangled Rashba-Split Shockley States on the Surface of Grey Arsenic.

We discover a pair of spin-polarized surface bands on the (111) face of grey arsenic by using angle-resolved photoemission spectroscopy (ARPES). In the occupied side, the pair resembles typical nearly-free-electron Shockley states observed on noble-metal surfaces. However, pump-probe ARPES reveals that the spin-polarized pair traverses the bulk band gap and that the crossing of the pair at Γ[over ¯] is topologically unavoidable. First-principles calculations well reproduce the bands and their nontrivial topology; the calculations also support that the surface states are of Shockley type because they arise from a band inversion caused by crystal field. The results provide compelling evidence that topological Shockley states are realized on As(111).

Emerging of canine kobuvirus in dogs in China, 2015.

Canine kobuvirus (CaKoV) is a newly emerging virus in dogs, which relates to the diarrhea of dogs. To investigate the CaKoV infection in dog population, fecal samples of dogs were collected from three provinces of China in 2015. The results of genetic analysis based on the complete VP1 gene showed that six CaKoVs isolates in this study were closely related with the Chinese canine originated isolate CH1 (90.6%-91.9% nucleotide identities). The phylogenetic analysis demonstrated that the Chinese isolates clustered into a unique branch compared with isolates from other countries. The present study suggested that the CaKoVs had established infection in Chinese dog population. The systematic epidemiological investigation should be further carried out to evaluate the prevalence of the CaKoV infection in China.

Compensated Semimetal LaSb with Unsaturated Magnetoresistance.

By combining angle-resolved photoemission spectroscopy and quantum oscillation measurements, we performed a comprehensive investigation on the electronic structure of LaSb, which exhibits near-quadratic extremely large magnetoresistance (XMR) without any sign of saturation at magnetic fields as high as 40 T. We clearly resolve one spherical and one intersecting-ellipsoidal hole Fermi surfaces (FSs) at the Brillouin zone (BZ) center Γ and one ellipsoidal electron FS at the BZ boundary X. The hole and electron carriers calculated from the enclosed FS volumes are perfectly compensated, and the carrier compensation is unaffected by temperature. We further reveal that LaSb is topologically trivial but shares many similarities with the Weyl semimetal TaAs family in the bulk electronic structure. Based on these results, we have examined the mechanisms that have been proposed so far to explain the near-quadratic XMR in semimetals.

The contribution of rare and common variants in 30 genes to risk nicotine dependence.

Genetic and functional studies have revealed that both common and rare variants of several nicotinic acetylcholine receptor subunits are associated with nicotine dependence (ND). In this study, we identified variants in 30 candidate genes including nicotinic receptors in 200 sib pairs selected from the Mid-South Tobacco Family population with equal numbers of African Americans (AAs) and European Americans (EAs). We selected 135 of the rare and common variants and genotyped them in the Mid-South Tobacco Case-Control (MSTCC) population, which consists of 3088 AAs and 1430 EAs. None of the genotyped common variants showed significant association with smoking status (smokers vs non-smokers), Fagerström Test for ND scores or indexed cigarettes per day after Bonferroni correction. Rare variants in NRXN1, CHRNA9, CHRNA2, NTRK2, GABBR2, GRIN3A, DNM1, NRXN2, NRXN3 and ARRB2 were significantly associated with smoking status in the MSTCC AA sample, with weighted sum statistic (WSS) P-values ranging from 2.42 × 10(-3) to 1.31 × 10(-4) after 10(6) phenotype rearrangements. We also observed a significant excess of rare nonsynonymous variants exclusive to EA smokers in NRXN1, CHRNA9, TAS2R38, GRIN3A, DBH, ANKK1/DRD2, NRXN3 and CDH13 with WSS P-values between 3.5 × 10(-5) and 1 × 10(-6). Variants rs142807401 (A432T) and rs139982841 (A452V) in CHRNA9 and variants V132L, V389L, rs34755188 (R480H) and rs75981117 (N549S) in GRIN3A are of particular interest because they are found in both the AA and EA samples. A significant aggregate contribution of rare and common coding variants in CHRNA9 to the risk for ND (SKAT-C: P=0.0012) was detected by applying the combined sum test in MSTCC EAs. Together, our results indicate that rare variants alone or combined with common variants in a subset of 30 biological candidate genes contribute substantially to the risk of ND.

Micro-computed tomography evaluation of the removal of calcium hydroxide medicament from C-shaped root canals of mandibular second molars.

AIM: To use micro-computed tomography (µ-CT) to evaluate the amount of calcium hydroxide [Ca(OH)2 ] remaining in the C-shaped root canals of mandibular second molars after attempting to remove it with passive ultrasonic and sonic irrigation. METHODOLOGY: Thirty mandibular second molars, 15 in C1 and 15 in C2 configurations as first identified by µ-CT, were divided into three groups (five C1 and five C2 in each group) for the three irrigation methods. All teeth were prepared to ProTaper Universal F2 and filled with Ca(OH)2 paste. The Ca(OH)2 was removed with F2 files and irrigation without agitation or with agitation using either EndoActivator or ultrasonics. µ-CT was used to measure the initial amount of Ca(OH)2 present. After removal of Ca(OH)2, µ-CT imaging was used to assess the percentage of volume of residual Ca(OH)2 in the canal. Data were analysed using one-way anova test. RESULTS: There was no significant difference in the mean volume of the root canal systems after instrumentation amongst the three groups. The three irrigation techniques left 2-17% of Ca(OH)2 in the root canals after removal. The mean volume of the remaining Ca(OH)2 was higher in the group without agitation than in the groups with sonic or ultrasonic agitation (P < 0.05). In the apical third, 68% of the canal space remained occupied by Ca(OH)2 when no agitation was used, whereas 28% and 31% remained filled by Ca(OH)2 in the EndoActivator and ultrasonic groups, respectively. There was no significant difference in the amount of residual Ca(OH)2 between the EndoActivator and ultrasonic groups. The proportion of remaining Ca(OH)2 in the apical canals was higher than in the middle and coronal canals in all groups (P < 0.05). CONCLUSIONS: A considerable proportion of the apical canal space remained filled with Ca(OH)2 in the C-shaped root canals after instrumentation and conventional needle irrigation. Although combining rotary instrumentation and irrigation with sonic or ultrasonic agitation reduced the amount of residual Ca(OH)2 in the C-shaped root canals, the large amount of calcium hydroxide in the critical apical area remains a concern. Alternative strategies should be considered in medication of the apical canal in C-shaped teeth.

The role of minority geographic distribution in waiting time for deceased donor kidney transplantation.

In the US, African Americans and other minority groups have longer wait times to deceased donor kidney transplantation than Caucasians. To date, the role of geographic distribution of racial and ethnic groups as a determinant of wait times has not been fully elucidated. Using the Scientific Registry of Transplant Recipients database, all registrants for kidney transplant between 2004 and 2007 (n=126,094) were analyzed from time of waitlisting until nonzero antigen mismatched deceased donor kidney transplant. Nationally, deceased donor transplantation occurred at a lower rate for African Americans (hazard ratio [HR] 0.85, confidence interval [CI] 0.83-0.87), Hispanics (HR 0.68, CI 0.66-0.70), Asians/Pacific Islanders (HR 0.77, CI 0.73-0.80) and Other minority groups (HR 0.74, CI 0.69-0.81) compared to Caucasians. Multivariate modeling for age, gender, cause of end-stage renal disease, ABO type, panel reactive antibody, HLA-DR frequency, expanded criteria donor status and prior kidney donation only partially accounted for this difference. Adjusting for these variables and organ procurement organization of listing, African Americans (HR 1.03, CI 1.00-1.06), Hispanics (HR 1.15, CI 1.10-1.19), Asians/Pacific Islanders (HR 1.36, CI 1.30-1.43) and Other minority groups (HR 1.00, CI 0.92-1.09) were transplanted at similar or higher rates than Caucasians. Our findings show that geographic location of waitlisted candidates is the most important contributor to racial disparities in waiting times for deceased donor kidney transplantation.

Correlation-induced self-doping in the iron-pnictide superconductor Ba2Ti2Fe2As4O.

The electronic structure of the iron-based superconductor Ba2Ti2Fe2As4O (Tc(onset)=23.5 K) has been investigated by using angle-resolved photoemission spectroscopy and combined local density approximation and dynamical mean field theory calculations. The electronic states near the Fermi level are dominated by both the Fe 3d and Ti 3d orbitals, indicating that the spacer layers separating different FeAs layers are also metallic. By counting the enclosed volumes of the Fermi surface sheets, we observe a large self-doping effect; i.e., 0.25 electrons per unit cell are transferred from the FeAs layer to the Ti2As2O layer, leaving the FeAs layer in a hole-doped state. This exotic behavior is successfully reproduced by our dynamical mean field calculations, in which the self-doping effect is attributed to the electronic correlations in the 3d shells. Our work provides an alternative route of effective doping without element substitution for iron-based superconductors.

Development of an indirect ELISA with epitope on nonstructural protein of Muscovy duck parvovirus for differentiating between infected and vaccinated Muscovy ducks.

UNLABELLED: The aim of this study was to develop an indirect enzyme-linked immunosorbent assay (i-ELISA) based on epitope AA503-509 (RANEPKE), which is on nonstructural protein of Muscovy duck parvovirus (MDPV). Sera (100) from negative and vaccinated Muscovy ducks were compared with infected sera (240) to establish the cut-off value of this i-ELISA. There was a significant difference between the positive and negative populations (P < 0·05). The adoption of this positive-negative threshold value for this i-ELISA assay resulted in specificity of 98·0%. This i-ELISA could be used as a diagnostic tool for differentiating infected Muscovy ducks from Muscovy ducks vaccinated with inactivated virus. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, we developed an i-ELISA based on epitope AA503-509 (RANEPKE), which is on nonstructural protein of MDPV. This i-ELISA could be used as a diagnostic tool for differentiating infected Muscovy ducks from Muscovy ducks vaccinated with inactivated virus.

Screening and analyzing genes associated with Amur tiger placental development.

The Amur tiger is a unique endangered species in the world, and thus, protection of its genetic resources is extremely important. In this study, an Amur tiger placenta cDNA library was constructed using the SMART cDNA Library Construction kit. A total of 508 colonies were sequenced, in which 205 (76%) genes were annotated and mapped to 74 KEGG pathways, including 29 metabolism, 29 genetic information processing, 4 environmental information processing, 7 cell motility, and 5 organismal system pathways. Additionally, PLAC8, PEG10 and IGF-II were identified after screening genes from the expressed sequence tags, and they were associated with placental development. These findings could lay the foundation for future functional genomic studies of the Amur tiger.

[Prospective randomized controlled study on clinical effects of autologous skin paste in repairing medium-thickness skin donor site wounds].

Objective: To explore the clinical effects of autologous skin paste in repairing medium-thickness skin donor site wounds. Methods: The prospective randomized controlled research method was applied. From October 2018 to December 2019, 18 patients with flame burn or hydrothermal scald, conforming to the inclusion criteria were admitted to Jinhua Hospital Affiliated to Zhejiang University School of Medicine, including 15 males and 3 females, aged (45±6) years. The wounds were repaired with medium-thickness skin grafts from thigh, and the wound area was (121±33) cm2 after medium-thickness skin grafting. The medium-thickness skin donor site wound in each patient was divided into 2 wounds in equal area and allocated into autologous skin paste group and conventional treatment group by flipping a coin, with 18 wounds in each group. The wounds in autologous skin paste group were repaired with skin paste prepared with remaining skin fragments after autologous medium-thickness skin grafting, and the wounds in conventional treatment group were covered with petroleum jelly gauze and fixed with sterile gauze. On 3, 7, 14, and 21 d after operation, the wound healing in 2 groups was observed, and the wound healing rate was calculated. The wound healing time in 2 groups was recorded. Occurrences of wound subcutaneous effusion and infection on 3, 7, 14, and 21 d after operation and wound ulceration in 3 months after operation were observed. In 6 months after operation, the Vancouver Scar Scale (VSS) was used to evaluate the scar formation of wounds in 2 groups. Data were statistically analyzed with analysis of variance for repeated measurement, chi-square test, and group t test. Results: The wounds in 2 groups did not heal on 3 and 7 d after operation. The wound healing rate in autologous skin paste group was (29.8±2.5)% and (95.6±4.7)% on 14 and 21 d after operation, which were significantly higher than (25.8±2.9)% and (82.6±8.9)% in conventional treatment group (t=4.3, 5.6, P<0.01). The wound healing time in autologous skin paste group was (21.8±1.6) d, which was significantly shorter than (25.6±2.0) d in conventional treatment group (t=6.24, P<0.01). On 3, 7, 14, and 21 d after operation, there were no complications such as subcutaneous effusion or infection in wounds of 2 groups. In 3 months after operation, ulceration occurred in wounds of 2 patients in autologous skin paste group, which was significantly less than 12 patients in conventional treatment group (χ2=11.688, P<0.01). The ulcerated wounds healed after dressing changes. In 6 months after operation, the VSS score of wounds in autologous skin paste group was (9.1±1.1) points, which was significantly lower than (11.3±1.2) points in conventional treatment group (t=-5.75, P<0.01). Conclusions: The remaining skin fragments after autologous medium-thickness skin grafting prepared into skin paste to repair medium-thickness skin donor site wounds can shorten wound healing time, improve wound healing quality, and reduce degree of scar hyperplasia, with a good clinical effect.

[Effect of autologous skin paste on repairing wound of donor site of medium-thickness skin graft].

Objective: To explore the effect of autologous skin paste on repairing wound of medium-thickness skin donor site. Methods: The prospective randomized controlled research method was applied. From October 2018 to December 2019, 18 patients with flame burn or hydrothermal scald, met the inclusion criteria were admitted to Jinhua Hospital Affiliated to Zhejiang University School of Medicine, including 15 males and 3 females, aged (45±6) years, and the wounds were repaired with medium-thickness skin grafts. The wound area after medium-thickness skin grafting was (121±33) cm2. The wound of donor site of medium-thickness skin graft in each patient was divided into 2 wounds in equal area and included into autologous skin paste group and conventional treatment group with random number table, with 18 wounds in each group.The wounds in autologous skin paste group were repaired with skin paste prepared with remaining skin fragments after autologous medium-thickness skin grafting, and the wounds in conventional treatment group were repaired with petroleum jelly gauze and sterile gauze. On 3, 7, 14, 21 d after operation, the wound healing in 2 groups was observed, and the wound healing rate was calculated. The wound healing time in 2 groups was recorded. Occurrences of subcutaneous effusion and infection on 3, 7, 14, 21 d after operation and wound rupture in 3 months after operation were observed. In 6 months after operation, the Vancouver scar scale (VSS) was used to evaluate the scar formation of wounds in 2 groups. Data were statistically analyzed with analysis of variance for repeated measurement, chi-square test, and group t test. Results: The wounds in 2 groups did not heal on 3 and 7 d after operation. The wound healing rate in autologous skin paste group was (29.8±2.5)% and (95.6±4.7)% on 14 and 21 d after operation, which were significantly higher than (25.8±2.9)% and (82.6±8.9)% in conventional treatment group (t=4.3, 5.6, P<0.01). The wound healing time in autologous skin paste group was (21.8±1.4) d, which was significantly shorter than (25.6±2.0) d in conventional treatment group (t=6.24, P<0.01). On 3, 7, 14, 21 d after operation, there were no complications such as subcutaneous effusion and infection in wounds of 2 groups. In 3 months after operation, ulceration occurred in wounds of 2 patients in autologous skin paste group, which was significantly less than 12 patients in conventional treatment group (χ2=11.688, P＜0.01). The wounds with ulceration healed after dressing change. In 6 months after operation, the VSS score of wounds in autologous skin paste group was (9.1±1.1) points, which was significantly lower than (11.3±1.2) points in conventional treatment group (t=-5.75, P＜0.01). Conclusion: The remaining fragments after autologous medium-thickness skin grafting are prepared into skin paste to repair wound of donor site of medium-thickness skin graft can shorten wound healing time, improve wound healing quality, reduce degree of scar hyperplasia, which has a good clinical effect.

Observation of a singular Weyl point surrounded by charged nodal walls in PtGa.

Constrained by the Nielsen-Ninomiya no-go theorem, in all so-far experimentally determined Weyl semimetals (WSMs) the Weyl points (WPs) always appear in pairs in the momentum space with no exception. As a consequence, Fermi arcs occur on surfaces which connect the projections of the WPs with opposite chiral charges. However, this situation can be circumvented in the case of unpaired WP, without relevant surface Fermi arc connecting its surface projection, appearing singularly, while its Berry curvature field is absorbed by nontrivial charged nodal walls. Here, combining angle-resolved photoemission spectroscopy with density functional theory calculations, we show experimentally that a singular Weyl point emerges in PtGa at the center of the Brillouin zone (BZ), which is surrounded by closed Weyl nodal walls located at the BZ boundaries and there is no Fermi arc connecting its surface projection. Our results reveal that nontrivial band crossings of different dimensionalities can emerge concomitantly in condensed matter, while their coexistence ensures the net topological charge of different dimensional topological objects to be zero. Our observation extends the applicable range of the original Nielsen-Ninomiya no-go theorem which was derived from zero dimensional paired WPs with opposite chirality.

Genome-wide association analyses suggested a novel mechanism for smoking behavior regulated by IL15.

Cigarette smoking is the leading preventable cause of death in the United States. Although smoking behavior has a significant genetic determination, the specific genes and associated mechanisms underlying the smoking behavior are largely unknown. Here, we carried out a genome-wide association study on smoking behavior in 840 Caucasians, including 417 males and 423 females, in which we examined approximately 380,000 single nucleotide polymorphisms (SNPs). We found that a cluster of nine SNPs upstream from the IL15 gene were associated with smoking status in males, with the most significant SNP, rs4956302, achieving a P-value (8.80 x 10(-8)) of genome-wide significance. Another SNP, rs17354547 that is highly conserved across multiple species achieved a P-value of 5.65 x 10(-5). These two SNPs, together with two additional SNPs (rs1402812 and rs4956396) were selected from the above nine SNPs for replication in an African-American sample containing 1251 subjects, including 412 males and 839 females. The SNP rs17354547 was replicated successfully in the male subgroup of the replication sample; it was associated with smoking quantity (SQ), the Heaviness of Smoking Index (HSI) and the Fagerstrom Test for Nicotine Dependence (FTND), with P-values of 0.031, 0.0046 and 0.019, respectively. In addition, a haplotype formed by rs17354547, rs1402812 and rs4956396 was also associated with SQ, HSI and FTND, achieving P-values of 0.039, 0.0093 and 0.0093, respectively. To further confirm our findings, we carried out an in silico replication study of the nine SNPs in a Framingham Heart Study sample containing 7623 Caucasians from 1731 families, among which, 3491 subjects were males and 4132 were females. Again, the male-specific association with smoking status was observed, for which seven of the nine SNPs achieved significant P-values (P<0.05) and two achieved marginally significant P-values (P<0.10) in males. Several of the nine SNPs, including the highly conserved one across species, rs17354547, are located at potential transcription factor binding sites, suggesting transcription regulation as a possible function for these SNPs. Through this function, the SNPs may modulate the gene expression of IL15, a key cytokine regulating immune function. As the immune system has long been recognized to influence drug addiction behavior, our association findings suggest a novel mechanism for smoking addiction involving immune modulation through the IL15 pathway.

Diversity of nitrogenase (nifH) genes pool in soybean field soil after continuous and rotational cropping.

Diazotrophs diversity in soybean is a topic requiring thorough investigation since the previous researches have focused on only rice, forest, grass, water, etc. In this research, iron-only nitrogenase nifH gene was as genetic marker. PCR-RFLP was used to investigate the difference of diazotrophs community diversity in the soil from the continuous cropping (CC) (the 5-yr tilling of soybean) and the rotational cropping (RC) (soybean-corn) soils in the northeast of China. A total of 36 isolates were genetically characterized. Most of the isolates closely related to Azospirillum and Azotobacter. Eighty-six unique nifH gene sequences were obtained by cloning of the respective PCR products in two soil samples. It was found that the diversity of nifH genes in CC changed obviously compared with RC. Phylogenetic analysis indicated that most of the clones clustered together in a high homogeneity with some sequence retrieved from environmental representatives. The sequence diversity of nifH genes was high and the members of the Alphaproteobacteria were predominant in both samples. The experimental study also revealed the two non-proteobacterial diazotrophs, firmicutes and euryarchaeota. Through this study, it can be assumed that different tillage perhaps affected the nifH gene-containing population diversity.

Beta-arrestins 1 and 2 are associated with nicotine dependence in European American smokers.

On the basis of our previous identified linkage regions for nicotine dependence (ND), we selected seven and four single nucleotide polymorphisms (SNPs) in the beta-arrestins 1 (ARRB1) and 2 (ARRB2), respectively, to determine the associations of the two genes with ND in a total of 2037 subjects from 602 nuclear families of European American (EA) and African American (AA) origin. ND was assessed by Smoking Quantity (SQ), the Heaviness of Smoking Index (HSI) and the Fagerström Test for ND (FTND) score. Individual SNP analysis indicated that SNPs rs472112 within ARRB1 and rs4790694 within ARRB2 in the EA sample was significantly associated with HSI and FTND score, and the association of rs4790694 for ARRB2 remained significant after correction for multiple testing. Haplotype analysis revealed that haplotype C-G-C-G-G-T within ARRB1 at a frequency of 20%, formed by SNPs rs528833, rs1320709, rs480174, rs5786130, rs611908 and rs472112, was positively associated with HSI and FTND in EAs. We also found a haplotype within ARRB2, C-C-A-T at a frequency of 10.7%, formed by SNPs rs3786047, rs4522461, rs1045280 and rs4790694, that showed a significant positive association with HSI and FTND in the EA sample. No significant associations for either individual SNPs or major haplotype of both ARRB1 and ARRB2 were found in the AA sample. Further, the strength of these associations increased after removing the SQ component from HSI and FTND scores in both the EA and AA samples, suggesting that ARRB1 and ARRB2 play an important role in biological processes involved in the regulation of smoking urgency (that is time to smoke first cigarette). In summary, our results provide the first evidence of a significant association for ARRB1 and ARRB2 variants with ND in an EA sample.

Genome-wide linkage scan for nicotine dependence in European Americans and its converging results with African Americans in the Mid-South Tobacco Family sample.

Previously, we reported a genome-wide scan for nicotine dependence (ND) in the African American (AA) sample of the Mid-South Tobacco Family (MSTF) cohort. In this study, we conducted a genome-wide scan in 629 individuals representing 200 nuclear families of European American (EA) origin of the MSTF cohort with the goals of identifying vulnerability loci for ND in the EAs and determining converging regions across the ethnic groups. We examined 385 autosomal microsatellite markers for ND, which was assessed by smoking quantity (SQ), the Heaviness of Smoking Index (HSI) and the Fagerström test for ND (FTND). After performing linkage analyses using various methods implemented in the GENEHUNTER and SAGE programs, we found eight regions on chromosomes 2, 4, 9-12, 17 and 18 that met the criteria for suggestive linkage to at least one ND measure in the EA sample. Of these, the region on chromosome 4 at 43 cM showed suggestive linkage to indexed SQ, the HSI and the FTND, and the region on chromosome 9 at 24 cM showed suggestive linkage to the HSI and the FTND. To increase detection power, we analyzed a combined AA and EA sample using age, gender and ethnicity as covariates and found that the region on chromosome 12 near marker D12S372 showed significant linkage to SQ. Additionally, we found six regions on chromosomes 9-11, 13 and 18 that showed suggestive linkage to at least one ND measure in the combined sample. When we compared the linkage peaks detected for ND among the two samples and a combined sample, we found that four regions on chromosomes 9 (two regions), 11 and 18 overlapped. On the other hand, we identified five regions on chromosomes 2, 4, 10, 12 and 17 that showed linkage to ND only in the EA sample, and two regions on chromosomes 10 and 13 that showed linkage to ND only in the AA sample. For those linkages identified in only one sample, we found that the combined analysis of AA plus EA samples actually decreased the linkage signal. This indicates that some chromosomal regions may be more homogenous than others across the ethnic samples. All regions except for the one on chromosome 12 have been detected at nominally significant levels in other studies, providing independent replication of ND loci in different populations.