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The microbial ecology of oligotrophic deep ocean sediments is understudied relative to their shallow counterparts, and this lack of understanding hampers our ability to predict responses to current and future perturbations. The Gulf of Mexico has experienced two of the largest accidental marine oil spills, the 1979 Ixtoc-1 blowout and the 2010 Deepwater Horizon (DWH) discharge. Here, microbial communities were characterized for 29 sites across multiple years in > 700 samples. The composition of the seafloor microbiome was broadly consistent across the region and was well approximated by the overlying water depth and depth within the sediment column, while geographic distance played a limited role. Biogeographical distributions were employed to generate predictive models for over 4000 OTU that leverage easy-to-obtain geospatial variables which are linked to measured sedimentary oxygen profiles. Depth stratification and putative niche diversification are evidenced by the distribution of taxa that mediate the microbial nitrogen cycle. Furthermore, these results demonstrate that sediments impacted by the DWH spill had returned to near baseline conditions after 2 years. The distributions of benthic microorganisms in the Gulf can be constrained, and moreover, deviations from these predictions may pinpoint impacted sites and aid in future response efforts or long-term stability studies.

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To advance understanding of the fate of hydrocarbons released from the Deepwater Horizon oil spill and deposited in marine sediments, this study characterized the microbial populations capable of anaerobic hydrocarbon degradation coupled with sulfate reduction in non-seep sediments of the northern Gulf of Mexico. Anaerobic, sediment-free enrichment cultures were obtained with either hexadecane or phenanthrene as sole carbon source and sulfate as a terminal electron acceptor. Phylogenetic analysis revealed that enriched microbial populations differed by hydrocarbon substrate, with abundant SSU rRNA gene amplicon sequences from hexadecane cultures showing high sequence identity (up to 98%) to Desulfatibacillum alkenivorans (family Desulfobacteraceae), while phenanthrene-enriched populations were most closely related to Desulfatiglans spp. (up to 95% sequence identity; family Desulfarculaceae). Assuming complete oxidation to CO2, observed stoichiometric ratios closely resembled the theoretical ratios of 12.25:1 for hexadecane and 8.25:1 for phenanthrene degradation coupled to sulfate reduction. Phenanthrene carboxylic acid was detected in the phenanthrene-degrading enrichment cultures, providing evidence to indicate carboxylation as an activation mechanism for phenanthrene degradation. Metagenome-assembled genomes (MAGs) revealed that phenanthrene degradation is likely mediated by novel genera or families of sulfate-reducing bacteria along with their fermentative syntrophic partners, and candidate genes linked to the degradation of aromatic hydrocarbons were detected for future study.

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ABSTRACT Objective: The purposes of this investigation were to determine the horizontal distances between the mandibular posterior teeth and the WALA ridge in a sample of Peruvians with normal occlusion and to compare them by tooth type, sex, arch side, and age groups. Methods: 65 dental casts of subjects with normal occlusion were collected. Posterior teeth, except for third molars, were evaluated. The horizontal distances between the occluso-gingival midpoints of the buccal surfaces (FA points) of each tooth and the WALA ridge were measured using a modified digital caliper. The values between each different tooth type within the sample were compared using the ANOVA and Scheffe tests, while comparisons by sex, arch side and age groups, using the Student's t-test. Results: The mean distances in the sample was 0.96 mm for first premolars, 1.45 mm for second premolars, 2.12 mm for first molars and 2.55 mm for second molars. Statistically significant differences between each of the four tooth types were found. There were no significant differences found between sex, arch side and age groups. Conclusion: The horizontal distances between the mandibular posterior teeth and the WALA ridge increased progressively from the first premolars to the second molars in Peruvians with normal occlusion. The WALA ridge was a good landmark to evaluate the positions of posterior teeth in Peruvians with normal occlusion.

RESUMO Objetivos: o objetivo dessa investigação foi determinar a distância horizontal entre os dentes posteroinferiores e a borda WALA, em uma amostra de peruanos com oclusão normal, e compará-la por tipo de dente, sexo, lado da arcada dentária e grupo etário. Métodos: foram selecionados 65 modelos dentários de indivíduos com oclusão normal, nos quais foram avaliados os dentes posteriores, com exceção dos terceiros molares. As distâncias horizontais entre o ponto oclusogengival médio da face vestibular (pontos EV) de cada dente e a borda WALA foram medidas utilizando-se um compasso digital modificado. Os testes de Scheffe e ANOVA foram usados para comparações entre os valores de cada tipo de dente estudado, enquanto o teste t de Student foi usado para as comparações entre sexos, lados da arcada e faixa etárias. Resultados: as distâncias médias nessa amostra foram de 0,96 mm para os primeiros pré-molares; 1,45 mm para os segundos pré-molares; 2,12 mm para os primeiros molares, e 2,55 mm para os segundos molares. Foram encontradas diferenças estatisticamente significativas entre cada um dos quatro tipos dentários. Não houve diferenças significativas entre os sexos, lados da arcada e grupos etários. Conclusão: nos peruanos com oclusão normal dessa amostra, as distâncias horizontais entre os dentes posteroinferiores e a borda WALA aumentaram progressivamente dos primeiros pré-molares para os segundos molares. Nesses pacientes, a borda WALA funcionou como um bom ponto de referência para se avaliar a posição dos dentes posteroinferiores.

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OBJECTIVE: The purposes of this investigation were to determine the horizontal distances between the mandibular posterior teeth and the WALA ridge in a sample of Peruvians with normal occlusion and to compare them by tooth type, sex, arch side, and age groups. METHODS: 65 dental casts of subjects with normal occlusion were collected. Posterior teeth, except for third molars, were evaluated. The horizontal distances between the occluso-gingival midpoints of the buccal surfaces (FA points) of each tooth and the WALA ridge were measured using a modified digital caliper. The values between each different tooth type within the sample were compared using the ANOVA and Scheffe tests, while comparisons by sex, arch side and age groups, using the Student's t-test. RESULTS: The mean distances in the sample was 0.96 mm for first premolars, 1.45 mm for second premolars, 2.12 mm for first molars and 2.55 mm for second molars. Statistically significant differences between each of the four tooth types were found. There were no significant differences found between sex, arch side and age groups. CONCLUSION: The horizontal distances between the mandibular posterior teeth and the WALA ridge increased progressively from the first premolars to the second molars in Peruvians with normal occlusion. The WALA ridge was a good landmark to evaluate the positions of posterior teeth in Peruvians with normal occlusion.

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The objective of this study was to investigate the impacts of the Deepwater Horizon (DWH) oil discharge at the seafloor as recorded in bottom sediments of the DeSoto Canyon region in the northeastern Gulf of Mexico. Through a close coupling of sedimentological, geochemical, and biological approaches, multiple independent lines of evidence from 11 sites sampled in November/December 2010 revealed that the upper ~1 cm depth interval is distinct from underlying sediments and results indicate that particles originated at the sea surface. Consistent dissimilarities in grain size over the surficial ~1 cm of sediments correspond to excess (234)Th depths, which indicates a lack of vertical mixing (bioturbation), suggesting the entire layer was deposited within a 4-5 month period. Further, a time series from four deep-sea sites sampled up to three additional times over the following two years revealed that excess (234)Th depths, accumulation rates, and (234)Th inventories decreased rapidly, within a few to several months after initial coring. The interpretation of a rapid sedimentation pulse is corroborated by stratification in solid phase Mn, which is linked to diagenesis and redox change, and the dramatic decrease in benthic formanifera density that was recorded in surficial sediments. Results are consistent with a brief depositional pulse that was also reported in previous studies of sediments, and marine snow formation in surface waters closer to the wellhead during the summer and fall of 2010. Although sediment input from the Mississippi River and advective transport may influence sedimentation on the seafloor in the DeSoto Canyon region, we conclude based on multidisciplinary evidence that the sedimentation pulse in late 2010 is the product of marine snow formation and is likely linked to the DWH discharge.

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A significant portion of oil from the recent Deepwater Horizon (DH) oil spill in the Gulf of Mexico was transported to the shoreline, where it may have severe ecological and economic consequences. The objectives of this study were (i) to identify and characterize predominant oil-degrading taxa that may be used as model hydrocarbon degraders or as microbial indicators of contamination and (ii) to characterize the in situ response of indigenous bacterial communities to oil contamination in beach ecosystems. This study was conducted at municipal Pensacola Beach, FL, where chemical analysis revealed weathered oil petroleum hydrocarbon (C8 to C40) concentrations ranging from 3.1 to 4,500 mg kg⁻¹ in beach sands. A total of 24 bacterial strains from 14 genera were isolated from oiled beach sands and confirmed as oil-degrading microorganisms. Isolated bacterial strains were primarily Gammaproteobacteria, including representatives of genera with known oil degraders (Alcanivorax, Marinobacter, Pseudomonas, and Acinetobacter). Sequence libraries generated from oiled sands revealed phylotypes that showed high sequence identity (up to 99%) to rRNA gene sequences from the oil-degrading bacterial isolates. The abundance of bacterial SSU rRNA gene sequences was ∼10-fold higher in oiled (0.44 × 107 to 10.2 × 107 copies g⁻¹) versus clean (0.024 × 107 to 1.4 × 107 copies g⁻¹) sand. Community analysis revealed a distinct response to oil contamination, and SSU rRNA gene abundance derived from the genus Alcanivorax showed the largest increase in relative abundance in contaminated samples. We conclude that oil contamination from the DH spill had a profound impact on the abundance and community composition of indigenous bacteria in Gulf beach sands, and our evidence points to members of the Gammaproteobacteria (Alcanivorax, Marinobacter) and Alphaproteobacteria (Rhodobacteraceae) as key players in oil degradation there.

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Aim: The aim of this study was to identify the prevalence of 3 different mandibular dental arch morphologies in individuals with natural normal occlusion. Methods: Fifty-one mandibular dental casts of Caucasian individuals with natural normal occlusion were digitized. Each was without a history of orthodontic treatment and presenting at least four of the six keys to normal occlusion described by Andrews. Twelve orthodontists evaluated the prevalence of the square, oval and tapered arch shapes by analyzing the mandibular digital images. Results: The most prevalent dental arch shape was oval (41%), followed by square (39%), and tapered (20%) shapes. Conclusions: During leveling and alignment phases, when elastic-alloy-wires are greatly used, the orthodontist could use any of the studied arch shapes (oval, square, tapered), once the prevalence of all of them was similar.

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INTRODUCTION: The aims of this study were to evaluate the distances between the mandibular permanent teeth and the alveolar process in Brazilians with normal occlusion and to compare them with normal American values. METHODS: We used 59 mandibular casts from untreated subjects who had permanent dentition and the 6 keys to normal occlusion. A computer program was used to calculate the distances between the dental reference points and the alveolar process for each tooth. The mean values were then compared to the normal values by applying the Student t test at a significance level of 0.05. RESULTS: The results showed a progressive increase of these distances from the anterior region (incisors) to the posterior region (molars), from 0.00 to 2.49 mm. All measurements had statistically significant differences from the American sample, except for the values for canines and first premolars. CONCLUSIONS: Brazilians with normal occlusion have more lingual crown positions for the incisors, second premolars, and molars compared with Americans with normal occlusion. Although these findings were statistically significant, they are unlikely to be clinically significant.

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