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"Lee, Allison"
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Marine microgels as a source of cloud condensation nuclei in the high Arctic
Marine microgels play an important role in regulating ocean basin-scale biogeochemical dynamics. In this paper, we demonstrate that, in the high Arctic, marine gels with unique physicochemical characteristics originate in the organic material produced by ice algae and/or phytoplankton in the surface water. The polymers in this dissolved organic pool assembled faster and with higher microgel yields than at other latitudes. The reversible phase transitions shown by these Arctic marine gels, as a function of pH, dimethylsulfide, and dimethylsulfoniopropionate concentrations, stimulate the gels to attain sizes below 1 μm in diameter. These marine gels were identified with an antibody probe specific toward material from the surface waters, sized, and quantified in airborne aerosol, fog, and cloud water, strongly suggesting that they dominate the available cloud condensation nuclei number population in the high Arctic (north of 80°N) during the summer season. Knowledge about emergent properties of marine gels provides important new insights into the processes controlling cloud formation and radiative forcing, and links the biology at the ocean surface with cloud properties and climate over the central Arctic Ocean and, probably, all oceans.
Journal Article
Ocean acidification conditions increase resilience of marine diatoms
The fate of diatoms in future acidified oceans could have dramatic implications on marine ecosystems, because they account for ~40% of marine primary production. Here, we quantify resilience of
Thalassiosira pseudonana
in mid-20th century (300 ppm CO
2
) and future (1000 ppm CO
2
) conditions that cause ocean acidification, using a stress test that probes its ability to recover from incrementally higher amount of low-dose ultraviolet A (UVA) and B (UVB) radiation and re-initiate growth in day–night cycles, limited by nitrogen. While all cultures eventually collapse, those growing at 300 ppm CO
2
succumb sooner. The underlying mechanism for collapse appears to be a system failure resulting from “loss of relational resilience,” that is, inability to adopt physiological states matched to N-availability and phase of the diurnal cycle. Importantly, under elevated CO
2
conditions diatoms sustain relational resilience over a longer timeframe, demonstrating increased resilience to future acidified ocean conditions. This stress test framework can be extended to evaluate and predict how various climate change associated stressors may impact microbial community resilience.
Diatoms account for 40% of marine primary production and their sensitivity to ocean acidification could have ecosystem-wide consequences. Here, the authors developed and applied a stress test, demonstrating that resilience of diatoms increases significantly in ocean acidification conditions.
Journal Article
Genome-wide diel growth state transitions in the diatom Thalassiosira pseudonana
Marine diatoms are important primary producers that thrive in diverse and dynamic environments. They do so, in theory, by sensing changing conditions and adapting their physiology accordingly. Using the model species Thalassiosira pseudonana , we conducted a detailed physiological and transcriptomic survey to measure the recurrent transcriptional changes that characterize typical diatom growth in batch culture. Roughly 40% of the transcriptome varied significantly and recurrently, reflecting large, reproducible cell-state transitions between four principal states: (i) “dawn,” following 12 h of darkness; (ii) “dusk,” following 12 h of light; (iii) exponential growth and nutrient repletion; and (iv) stationary phase and nutrient depletion. Increases in expression of thousands of genes at the end of the reoccurring dark periods (dawn), including those involved in photosynthesis (e.g., ribulose-1,5-bisphosphate carboxylase oxygenase genes rbcS and rbcL), imply large-scale anticipatory circadian mechanisms at the level of gene regulation. Repeated shifts in the transcript levels of hundreds of genes encoding sensory, signaling, and regulatory functions accompanied the four cell-state transitions, providing a preliminary map of the highly coordinated gene regulatory program under varying conditions. Several putative light sensing and signaling proteins were associated with recurrent diel transitions, suggesting that these genes may be involved in light-sensitive and circadian regulation of cell state. These results begin to explain, in comprehensive detail, how the diatom gene regulatory program operates under varying environmental conditions. Detailed knowledge of this dynamic molecular process will be invaluable for new hypothesis generation and the interpretation of genetic, environmental, and metatranscriptomic data from field studies.
Journal Article
الدليل الشامل في تربية الأطفال (للوالدين والمعلمين والمهتمين)
يقدم هذا الكتاب وصفا لخصائص نمو الطفل ومؤشراته من لحظة الولادة وحتى سن السادسة عشرة من عمره. مقسما هذه الفترة من عمر الطفل إلى مراحل متعددة وفي كل مرحلة يناقش مؤشرات النمو البدنية والعقلية والعاطفية والاجتماعية والأخلاقية والدينية والثقافية، ويقدم إرشادات مهمة للوالدين والمربين من معلمين ومعلمات ابتداء من مرحلة الحضانة حتى بداية المرحلة الثانوية، وتمتاز الإرشادات المقدمة في هذا الكتاب بأنها واقعية ونابعة من الخبرة العملية للمؤلف، كما تمتاز بضرب أمثلة تطبيقية على التعاملات بين المربي والأطفال في مختلف مراحل نموهم، وقد خصص المؤلف فصلا خاصا لمناقشة احتياجات الأطفال المعاقين وذوي الحاجات الخاصة. لا يستغنى عن هذا الكتاب كل أم وكل أب يحرص على تربية أبنائه وتنشئتهم تنشئة سليمة، وغني عن القول إن الاطلاع على هذا الكتاب أمر ضروري لكل مربية وكل معلمة ومعلم يحرص على مراقبة الله -سبحانه وتعالى- في تأدية واجبه وإتقان عمله.
BOOK
Amygdala-ventral striatum circuit activation decreases long-term fear
In humans, activation of the ventral striatum, a region associated with reward processing, is associated with the extinction of fear, a goal in the treatment of fear-related disorders. This evidence suggests that extinction of aversive memories engages reward-related circuits, but a causal relationship between activity in a reward circuit and fear extinction has not been demonstrated. Here, we identify a basolateral amygdala (BLA)-ventral striatum (NAc) pathway that is activated by extinction training. Enhanced recruitment of this circuit during extinction learning, either by pairing reward with fear extinction training or by optogenetic stimulation of this circuit during fear extinction, reduces the return of fear that normally follows extinction training. Our findings thus identify a specific BLA-NAc reward circuit that can regulate the persistence of fear extinction and point toward a potential therapeutic target for disorders in which the return of fear following extinction therapy is an obstacle to treatment.
Journal Article
Gloving up for the fight against racial and ethnic disparities in obstetric anesthesia care
[4] (New York State Perinatal Database 1998–2003; 81,883 patients) similarly found that when they tested the interaction between patient race/ethnicity and insurance status in a multivariate model, the rate of epidural analgesia did not vary for black patients regardless of type of insurance coverage. Broad adoption and implementation of existing safety initiatives such as the Council on Women's Healthcare Maternal Patient Safety Bundles and the California Maternal Quality Care Collaborative (CMQCC) toolkits can help to raise the level of care for all patients [12,13]. [...]we must reflect on implicit or unconscious bias in the healthcare workforce, which is notoriously difficult to rectify and requires a multidimensional approach [18,19].
Journal Article