Dissolved trace metal concentrations from depth profiles during RVIB Nathaniel B. Palmer cruise NBP16-08 in the Southern Ocean from 2016-09-11 to 2016-10-10

Dataset: NBP1608 TMs: stationsDissolved trace metal concentrations from depth profiles during RVIB Nathaniel B. Palmer cruise NBP16-08 in the Southern Ocean from 2016-09-11 to 2016-10-10. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/781773NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443483, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443474, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-14436462020-06-0

Phytoplankton Plastid Proteomics: Cracking Open Diatoms to Understand Plastid Biochemistry Under Iron Limitation

Diatoms, such as Thalassiosira pseudonana, are important oceanic primary producers, as they sequester carbon dioxide (CO₂) out of the atmosphere, die, and precipitate to the ocean floor. In many areas of the world’s oceans, phytoplankton, such as diatoms, are limited in growth by the availability of iron (Fe). Fe is an essential nutrient for phytoplankton, as it is central in the electron transport chain component of photosynthesis. Through this study, we examined if Fe-limitation makes a significant difference in the proteins expressed within the chloroplast, the power source for diatoms. Here, we utilized a new plastid isolation technique specific to diatoms and completed 14 mass spectrometry experiments to determine how many proteins transit the plastid membrane, if there are any differences in the expressed proteomes within the plastid grown under Fe-replete and Fe-limited conditions, and what those differences are. Over 900 unique proteins were identified from the isolated plastids, and cluster analyses of the data verified that statistical differences are present between the Fe-replete and Fe-limited growth conditions. Furthermore, our plastid proteome is in agreement with many of the recognized proteins previously discovered in land plant plastids, suggesting the isolation method followed by proteomic mass spectrometry is valid and sensitive. Through the isolation and analysis of plastid proteins, as shown here, scientists can now better identify which nutrients and/or trace metals directly affect diatom photosynthetic capacity so they can design better experiments to increase CO₂ fixation rates

Thalassiosira spp. Community Composition Shifts in Response to Chemical and Physical Forcing in the Northeast Pacific Ocean

Diatoms are genetically diverse unicellular photosynthetic eukaryotes that are key primary producers in the ocean. Many of the over 100 extant diatom species in the cosmopolitan genus Thalassiosira are difficult to distinguish in mixed populations using light microscopy. Here, we examine shifts in Thalassiosira spp. composition along a coastal to open ocean transect that encountered a 3-month-old Haida eddy in the northeast Pacific Ocean. To quantify shifts in Thalassiosira species composition, we developed a targeted automated ribosomal intergenic spacer analysis (ARISA) method to identify Thalassiosira spp. in environmental samples. As many specific fragment lengths are indicative of individual Thalassiosira spp., the ARISA method is a useful screening tool to identify changes in the relative abundance and distribution of specific species. The method also enabled us to assess changes in Thalassiosira community composition in response to chemical and physical forcing. Thalassiosira spp. community composition in the core of a 3-month-old Haida eddy remained largely (\u3e80%) similar over a 2-week period, despite moving 24 km southwestward. Shifts in Thalassiosira species correlated with changes in dissolved iron (Fe) and temperature throughout the sampling period. Simultaneously tracking community composition and relative abundance of Thalassiosira species within the physical and chemical context they occurred allowed us to identify quantitative linkages between environmental conditions and community response

\u3cem\u3eThalassiosira spp.\u3c/em\u3e Community Composition Shifts in Response to Chemical and Physical Forcing in the Northeast Pacific Ocean

Diatoms are genetically diverse unicellular photosynthetic eukaryotes that are key primary producers in the ocean. Many of the over 100 extant diatom species in the cosmopolitan genus Thalassiosira are difficult to distinguish in mixed populations using light microscopy. Here, we examine shifts in Thalassiosira spp. composition along a coastal to open ocean transect that encountered a 3-month-old Haida eddy in the northeast Pacific Ocean. To quantify shifts in Thalassiosira species composition, we developed a targeted automated ribosomal intergenic spacer analysis (ARISA) method to identify Thalassiosira spp. in environmental samples. As many specific fragment lengths are indicative of individual Thalassiosira spp., the ARISA method is a useful screening tool to identify changes in the relative abundance and distribution of specific species. The method also enabled us to assess changes in Thalassiosira community composition in response to chemical and physical forcing. Thalassiosira spp. community composition in the core of a 3-month-old Haida eddy remained largely (\u3e80%) similar over a 2-week period, despite moving 24 km southwestward. Shifts in Thalassiosira species correlated with changes in dissolved iron (Fe) and temperature throughout the sampling period. Simultaneously tracking community composition and relative abundance of Thalassiosira species within the physical and chemical context they occurred allowed us to identify quantitative linkages between environmental conditions and community response

Characterization of Putative Iron Responsive Genes as Species-Specific Indicators of Iron Stress in Thalassiosiroid Diatoms

Iron (Fe) availability restricts diatom growth and primary production in large areas of the oceans. It is a challenge to assess the bulk Fe nutritional health of natural diatom populations, since species can differ in their physiological and molecular responses to Fe limitation. We assayed expression of selected genes in diatoms from the Thalassiosira genus to assess their potential utility as species-specific molecular markers to indicate Fe status in natural diatom assemblages. In this study, we compared the expression of the photosynthetic genes encoding ferredoxin (a Fe-requiring protein) and flavodoxin (a Fe-free protein) in culture experiments with Fe replete and Fe stressed Thalassiosira pseudonana (CCMP 1335) isolated from coastal waters and Thalassiosira weissflogii (CCMP 1010) isolated from the open ocean. In T. pseudonana, expression of flavodoxin and ferredoxin genes were not sensitive to Fe status but were found to display diel periodicities. In T. weissflogii, expression of flavodoxin was highly responsive to iron levels and was only detectable when cultures were Fe limited. Flavodoxin genes have been duplicated in most diatoms with available genome data and we show that T. pseudonana has lost its copy related to the Fe-responsive copy in T. weissflogii. We also examined the expression of genes for a putative high affinity, copper (Cu)-dependent Fe uptake system in T. pseudonana. Our results indicate that genes encoding putative Cu transporters, a multi-Cu oxidase, and a Fe reductase are not linked to Fe status. The expression of a second putative Fe reductase increased in Fe limited cultures, but this gene was also highly expressed in Fe replete cultures, indicating it may not be a useful marker in the field. Our findings highlight that Fe metabolism may differ among diatoms even within a genus and show a need to validate responses in different species as part of the development pipeline for genetic markers of Fe status in field populations

Growth and CD4 patterns of adolescents living with perinatally acquired HIV worldwide, a CIPHER cohort collaboration analysis.

INTRODUCTION Adolescents living with HIV are subject to multiple co-morbidities, including growth retardation and immunodeficiency. We describe growth and CD4 evolution during adolescence using data from the Collaborative Initiative for Paediatric HIV Education and Research (CIPHER) global project. METHODS Data were collected between 1994 and 2015 from 11 CIPHER networks worldwide. Adolescents with perinatally acquired HIV infection (APH) who initiated antiretroviral therapy (ART) before age 10 years, with at least one height or CD4 count measurement while aged 10-17 years, were included. Growth was measured using height-for-age Z-scores (HAZ, stunting if <-2 SD, WHO growth charts). Linear mixed-effects models were used to study the evolution of each outcome between ages 10 and 17. For growth, sex-specific models with fractional polynomials were used to model non-linear relationships for age at ART initiation, HAZ at age 10 and time, defined as current age from 10 to 17 years of age. RESULTS A total of 20,939 and 19,557 APH were included for the growth and CD4 analyses, respectively. Half were females, two-thirds lived in East and Southern Africa, and median age at ART initiation ranged from 7 years in sub-Saharan African regions. At age 10, stunting ranged from 6% in North America and Europe to 39% in the Asia-Pacific; 19% overall had CD4 counts <500 cells/mm3 . Across adolescence, higher HAZ was observed in females and among those in high-income countries. APH with stunting at age 10 and those with late ART initiation (after age 5) had the largest HAZ gains during adolescence, but these gains were insufficient to catch-up with non-stunted, early ART-treated adolescents. From age 10 to 16 years, mean CD4 counts declined from 768 to 607 cells/mm3 . This decline was observed across all regions, in males and females. CONCLUSIONS Growth patterns during adolescence differed substantially by sex and region, while CD4 patterns were similar, with an observed CD4 decline that needs further investigation. Early diagnosis and timely initiation of treatment in early childhood to prevent growth retardation and immunodeficiency are critical to improving APH growth and CD4 outcomes by the time they reach adulthood

Chlorophyll and phaeopigment concentrations from incubation experiments performed with amended Southern Drake Passage on RVIB Nathaniel B. Palmer cruise NBP 16-08 from September to October 2016

Dataset: NBP1608 INC PIGMENTSThis dataset includes chlorophyll and phaeopigment concentrations from incubation experiments performed with amended Southern Drake Passage on RVIB Nathaniel B. Palmer cruise NBP 16-08 from September to October 2016. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/742206NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443483, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443474, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-144364

Chlorophyll and phaeopigment concentrations from near-surface profiles collected using the conventional CTD in the Southern Drake Passage and Antarctic Peninsular region on RVIB Nathaniel B. Palmer cruise NBP 16-08 from September to October 2016

Dataset: NBP1608 STN PIGMENTSThis dataset includes chlorophyll and phaeopigment concentrations from near-surface profiles collected using the conventional CTD in the Southern Drake Passage and Antarctic Peninsular region on RVIB Nathaniel B. Palmer cruise NBP 16-08 from September to October 2016. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/740939NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443483, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443474, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-144364

​Dissolved trace metal concentrations for Incubation 3, initiated September 27th, 2016 on RVIB Nathaniel B. Palmer cruise NBP16-08 in the Southern Ocean

Dataset: NBP1608 TMs: Incubation 3​Dissolved trace metal concentrations for Incubation 3, initiated September 27th, 2016 on RVIB Nathaniel B. Palmer cruise NBP16-08 in the Southern Ocean. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/781841NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443483, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443474, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-14436462020-06-0

Dissolved macronutrient concentrations from incubation experiments performed on RVIB Nathaniel B. Palmer cruise NBP 16-08 from September to October 2016

Dataset: NBP1608 Incubation NutrientsDissolved macronutrient concentrations from incubation experiments performed on RVIB Nathaniel B. Palmer cruise NBP 16-08 from September to October 2016. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/743072NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443483, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-1443474, NSF Office of Polar Programs (formerly NSF PLR) (NSF OPP) OPP-144364