Anatomy of the fetal membranes: insights from spinning disk confocal microscopy.

PURPOSE: The fetal membranes are essential for the maintenance of pregnancy, and their integrity until parturition is critical for both fetal and maternal health. Preterm premature rupture of the membranes (pPROM) is known to be an indicator of preterm birth, but the underlying architectural and mechanical changes that lead to fetal membrane failure are not yet fully understood. The aim of this study was to gain new insights into the anatomy of the fetal membrane and to establish a tissue processing and staining protocol suitable for future prospective cohort studies. METHODS: In this proof of principle study, we collected fetal membranes from women undergoing vaginal delivery or cesarean section. Small membrane sections were then fixed, stained for nucleic acids, actin, and collagen using fluorescent probes, and subsequently imaged in three dimensions using a spinning disk confocal microscope. RESULTS: Four fetal membranes of different types were successfully processed and imaged after establishing a suitable protocol. Cellular and nuclear outlines are clearly visible in all cases, especially in the uppermost membrane layer. Focal membrane (micro) fractures could be identified in several samples. CONCLUSION: The presented method proves to be well suited to determine whether and how the occurrence of membrane (micro) fractures and cellular jamming correlate with the timing of membrane rupture and the mode of delivery. In future measurements, this method could be combined with mechanical probing techniques to compare optical and mechanical sample information.

Characteristics of annual NH3 emissions from a conventional vegetable field under various nitrogen management strategies.

High N-fertilizer applications to conventional vegetable production systems are associated with substantial emissions of NH3, a key substance that triggers haze pollution and ecosystem eutrophication and thus, causing considerable damage to human and ecosystem health. While N fertilization effects on NH3 volatilization from cereal crops have been relatively well studied, little is known about the magnitude and yield-scaled emissions of NH3 from vegetable systems. Here we report on a 2-year field study investigating the effect of various types and rates of fertilizer application on NH3 emissions and crop yields for a pepper-lettuce-cabbage rotation system in southwest China. Our results show that both NH3 emissions and direct emission factors of applied N varied largely across seasons over the 2-year period, highlighting the importance of measurements spanning entire cropping years. Across all treatments varying from solely applying urea fertilizers to only using organic manures, annual NH3 emissions ranged from 0.64 to 92.4 kg N ha-1 yr-1 (or 0.07-6.84 g N kg-1 dry matter), equivalent to 0.05-5.99% of the applied N. At annual scale, NH3 emissions correlated positively with soil δ15N values, indicating that soil δ15N may be used as an indicator for NH3 losses. NH3 emissions from treatments fertilized partially or fully with manure were significantly lower compared with the urea fertilized treatment, while vegetable yields remained unaffected. Moreover, full substitution of urea by manure as compared to the partial substitution further reduced the yield-scaled annual NH3 emissions by 79.0-92.4%. Across all vegetable seasons, there is a significant negative relationship between yield-scaled NH3 emissions and crop N use efficiency. Overall, our results suggest that substituting urea by manure and reducing total N inputs by 30-50% allows to reduce NH3 emissions without jeopardizing yields. Such a change in management provides a feasible option to achieve environmental sustainability and food security in conventional vegetable systems.

Divalent Lanthanide Tetraisobutylaluminates: Reactivity and Living Isoprene Polymerization.

Lanthanide (Ln) tetraisobutylaluminates constitute key components in commercial 1,3-diene polymerization catalysts, and likewise are the homogeneous rare-earth-metal catalysts of prime industrial importance. Discrete divalent rare-earth-metal complexes [Ln(AliBu4 )2 ] (Ln=Sm, Eu, Yb) reported here display the first structurally characterized homoleptic metal tetraisobutylaluminates. Treatment of [Ln(AliBu4 )2 ] with C2 Cl6 gives access to SmII /SmIII mixed-valence cluster [Sm6 Cl8 (AliBu4 )6 ] and the YbII cluster [Yb4 Cl4 (AliBu4 )4 ], respectively. Reaction with B(C6 F5 )3 leads to hydride abstraction and formation of arene-coordinated hydroborates such as [Sm{HB(C6 F5 )3 }2 (toluene)2 ]. Complexes [Ln(AliBu4 )2 ] engage in single-component isoprene polymerization, affording high cis-1,4 polyisoprenes with narrow molecular weight distributions. Binary [Yb(AliBu4 )2 ]/[HNPhMe2 ][B(C6 F5 )4 ] fabricates polyisoprene in a perfectly living manner. The catalytically active species are scrutinized by NMR spectroscopy.

A WNT protein therapeutic accelerates consolidation of a bone graft substitute in a pre-clinical sinus augmentation model.

AIM: Autologous bone grafts consolidate faster than bone graft substitutes (BGSs) but resorb over time, which compromises implant support. We hypothesized that differences in consolidation rates affected the mechanical properties of grafts and implant stability, and tested whether a pro-osteogenic protein, liposomal WNT3A (L-WNT3A), could accelerate graft consolidation. MATERIALS AND METHODS: A transgenic mouse model of sinus augmentation with immunohistochemistry, enzymatic assays, and histology were used to quantitatively evaluate the osteogenic properties of autografts and BGSs. Composite and finite element modelling compared changes in the mechanical properties of grafts during healing until consolidation, and secondary implant stability following remodelling activities. BGSs were combined with L-WNT3A and tested for its osteogenic potential. RESULTS: Compared with autografts, BGSs were bioinert and lacked osteoprogenitor cells. While in autografted sinuses, new bone arose evenly from all living autograft particles, new bone around BGSs solely initiated at the sinus floor, from the internal maxillary periosteum. WNT treatment of BGSs resulted in significantly higher expression levels of pro-osteogenic proteins (Osterix, Collagen I, alkaline phosphatase) and lower levels of bone-resorbing activity (tartrate-resistant acid phosphatase activity); together, these features culminated in faster new bone formation, comparable to that of an autograft. CONCLUSIONS: WNT-treated BGSs supported faster consolidation, and because BGSs typically resist resorption, their use may be superior to autografts for sinus augmentation.

Biology of sinus floor augmentation with an autograft versus a bone graft substitute in a preclinical in vivo experimental model.

OBJECTIVES: Compared to autografts, bone graft substitutes are slower to consolidate. If we understood why, this might open strategies to accelerate new bone formation and thus shorten the time to implant placement. In this study, we aimed at comparing autologous bone graft with a bovine bone graft substitute in a preclinical sinus lift model. MATERIALS AND METHODS: The mouse posterior paranasal sinus served as a recipient site for grafting. Autograft from the oral cavity was compared against bone graft substitute using molecular, cellular, and histological analyses conducted on post-grafting days (PSD) 0, 9, 18, and 120. RESULTS: Either autografts or bone graft substitutes were positioned on the sinus floor and remained in situ throughout the study. At the time of grafting and until day 9, bone graft substitutes were devoid of cells and alkaline phosphatase (ALP) activity while autografts were comprised of viable cells and showed strong ALP (mineralization) activity. Consequently, new bone formed faster in autografts compared to bone graft substitutes (140.21 ± 41.21 µm vs. 41.70 ± 10.09 µm, respectively, PSD9, p = .0143). By PSD18, osteogenesis was evident in autografted and xenografted sites. Osteoclasts identified by tartrate resistant acid phosphatase attached to, but did not resorb the bone graft substitute matrix. Autograft matrix, however, underwent extensive resorption. Transgenic mice revealed that Wnt-responsive osteoprogenitor cells originated primarily from the internal periosteum of the maxillary bone, and not from the Schneiderian membrane. CONCLUSION: Autografts produce new bone sooner, but bovine bone graft substitutes eventually consolidate and then resist resorption. Enhancing osteoprogenitor cell recruitment to a bone graft substitute constitutes a viable strategy for accelerating bone formation in a sinus lift procedure.

Simultaneous quantification of N2 , NH3 and N2 O emissions from a flooded paddy field under different N fertilization regimes.

Gaseous nitrogen (N) emissions, especially emissions of dinitrogen (N2 ) and ammonia (NH3 ), have long been considered as the major pathways of N loss from flooded rice paddies. However, no studies have simultaneously evaluated the overall response of gaseous N losses to improved N fertilization practices due to the difficulties to directly measure N2 emissions from paddy soils. We simultaneously quantified emissions of N2 (using membrane inlet mass spectrometry), NH3 and nitrous oxide (N2 O) from a flooded paddy field in southern China over an entire rice-growing season. Our field experiment included three treatments: a control treatment (no N addition) and two N fertilizer (220 kg N/ha) application methods, the traditional surface application of N fertilizer and the incorporation of N fertilizer into the soil. Our results show that over the rice-growing season, the cumulative gaseous N losses from the surface application treatment accounted for 13.5% (N2 ), 19.1% (NH3 ), 0.2% (N2 O) and 32.8% (total gaseous N loss) of the applied N fertilizer. Compared with the surface application treatment, the incorporation of N fertilizer into the soil decreased the emissions of NH3 , N2 and N2 O by 14.2%, 13.3% and 42.5%, respectively. Overall, the incorporation of N fertilizer into the soil significantly reduced the total gaseous N loss by 13.8%, improved the fertilizer N use efficiency by 14.4%, increased the rice yield by 13.9% and reduced the gaseous N loss intensity (gaseous N loss/rice yield) by 24.3%. Our results indicate that the incorporation of N fertilizer into the soil is an effective agricultural management practice in ensuring food security and environmental sustainability in flooded paddy ecosystems.

Quality of life and associated factors after surgical treatment of vulvar cancer by vulvar field resection (VFR).

PURPOSE: To investigate patient-reported quality of life (QoL) and associated factors in vulvar cancer patients treated surgically by vulvar field resection (VFR) without adjuvant radiation. METHODS: We retrospectively evaluated patient-reported QoL as part of the prospective monocentric VFR trial using the 30-item European Organization for Research and Treatment of Cancer quality-of-life questionnaire (EORTC QLQ-C30) supplemented by a question assessing sexual activity. All patients had been treated by VFR and no participant had received adjuvant radiotherapy. The gynecologic cancer lymphedema questionnaire (GCLQ) was used to determine the presence of lymphedema. Structured telephone interviews were conducted to assess postoperative sequelae and long-term complications. RESULTS: Forty-three VFR patients (median age 63 years) were available for QoL assessment. Thirty-eight (88%) had received inguinal lymph-node dissection in addition to VFR. Mean global QoL (global health status) rating among all patients was 66.1 (± 25.5) on a scale from 0 to 100 with higher scores indicating better QoL. Higher GCLQ scores were significantly associated with lower global QoL scores (Spearman's rank correlation ρ =- 0.7, p < 0.0001). The presence of preoperative co-morbidities and postoperative wound-healing complications were also linked to reduced QoL (p < 0.01 for both). In a multivariable regression model, there was a significant interaction between preoperative co-morbidities and wound-healing complications with regard to global QoL (p < 0.05). CONCLUSION: Overall, VFR patients exhibit good quality of life postoperatively. The presence of lymphedema, wound-healing complications, and preoperative morbidities were associated with reduced QoL. Prospective longitudinal studies have to confirm our findings in the future.

Surgical resection based on ontogenetic cancer field theory for cervical cancer: mature results from a single-centre, prospective, observational, cohort study.

BACKGROUND: Previous findings from our centre suggest that carcinoma of the cervix propagates within ontogenetic cancer fields, tissue compartments defined by staged morphogenesis. We aimed to determine whether surgical treatment that accounts for stage-associated, ontogenetic cancer fields and their associated lymphoid tissues results in locoregional tumour control without the need for adjuvant radiotherapy. METHODS: We did the final clinical and histopathological evaluation of data from, the single-centre, observational, cohort study, the Leipzig School Mesometrial Resection Study. Patients of any age with stage IB1, IB2, IIA1, IIA2, or IIB cervical cancer (according to 2009 International Federation of Gynecology and Obstetrics [FIGO]) had total mesometrial resection or extended mesometrial resection and therapeutic lymph node dissection, done on the basis of ontogenetic cancer fields. We defined sentinel node, first-line, second-line, and third-line lymph node regions as progressive regional cancer fields. Primary outcomes were disease-specific survival and recurrence-free survival, and treatment-related morbidity (assessed with the Franco-Italian glossary). Applying Cox proportional hazard models, ontogenetic local (T) and regional (N) tumour staging was compared with pathological T and N staging. This trial is registered with the German Clinical Trials Register, number DRKS00015171. FINDINGS: Between Oct 16, 1999, and June 27, 2017, 523 patients were treated per protocol and followed up for a median of 61·8 months (IQR 49·3-94·8). In 495 patients with cervical cancer treated with cancer field surgery, 5-year disease-specific survival was 89·4% (95% CI 86·5-92·4) and recurrence-free survival was 83·1% (79·7-86·6). In the per-protocol population of 523 patients, treatment-related morbidity comprised 112 (21%) grade 2 and 15 (3%) grade 3 complications. The most common moderate and severe treatment-related complications and sequelae were wound dehiscence (17 [3%]), hydronephrosis (17 [3%]), bowel obstruction (26 [5%]), and lymph oedema (33 [6%]). One patient (<1%), who received total mesometrial resection, died from postoperative brain infarction. INTERPRETATION: Total or extended mesometrial resection with therapeutic lymph node dissection based on ontogenetic cancer fields results in good survival outcomes of patients with cervical cancer in our institution, but needs to be investigated further in multicentre trials. FUNDING: Leipzig School of Radical Pelvic Surgery, University of Leipzig Medical School, and the Gynecologic Oncology Research Foundation.

Cu+ Contributes to the Orange Carotenoid Protein-Related Phycobilisome Fluorescence Quenching and Photoprotection in Cyanobacteria.

Photosynthesis starts with absorption of light energy by using light-harvesting antenna complexes (LHCs). Overexcitation of LHCs and subsequent photosystems, however, is damaging and can be lethal. The orange carotenoid protein (OCP) protects most cyanobacteria from photodamage by dissipating excessive excitation energy harvested by phycobilisomes (PBS, LHCs) as heat. OCP has two states: the orange, inactive OCP (OCPO) and the red, active OCP (OCPR), with the latter able to bind PBS at a ratio of 2:1 and execute photoprotection. Conversion of OCPO to OCPR is driven by blue light absorption. Previous work indicated that in the presence of Cu2+, photoactivation of OCP can result in it being locked in its red form OCPR. The molecular mechanism of such chemical conversion, however, remains unclear. Here, we demonstrated that Cu+ can convert OCPO to OCPR under anaerobic conditions independent of light illumination. Interestingly, in the presence of Cu2+ and ascorbic acid, a ubiquitous reductant in photosynthetic organisms, the conversion of OCPO to OCPR can also take place spontaneously in the dark, indicative of a locked OCPR-Cu+ complex. Furthermore, our functional and structural studies indicate that OCPR-Cu+ can interact with PBS and trigger PBS fluorescence quenching. We hypothesize that copper ion, a redox-active component, may synergistically play an important role in the regulation of nonphotochemical quenching in cyanobacteria under stress conditions.

Far-red light acclimation in diverse oxygenic photosynthetic organisms.

Oxygenic photosynthesis has historically been considered limited to be driven by the wavelengths of visible light. However, in the last few decades, various adaptations have been discovered that allow algae, cyanobacteria, and even plants to utilize longer wavelength light in the far-red spectral range. These adaptations provide distinct advantages to the species possessing them, allowing the effective utilization of shade light under highly filtered light environments. In prokaryotes, these adaptations include the production of far-red-absorbing chlorophylls d and f and the remodeling of phycobilisome antennas and reaction centers. Eukaryotes express specialized light-harvesting pigment-protein complexes that use interactions between pigments and their protein environment to spectrally tune the absorption of chlorophyll a. If these adaptations could be applied to crop plants, a potentially significant increase in photon utilization in lower shaded leaves could be realized, improving crop yields.

Excitation energy transfer in the far-red absorbing violaxanthin/vaucheriaxanthin chlorophyll a complex from the eustigmatophyte alga FP5.

This work highlights spectroscopic investigations on a new representative of photosynthetic antenna complexes in the LHC family, a putative violaxanthin/vaucheriaxanthin chlorophyll a (VCP) antenna complex from a freshwater Eustigmatophyte alga FP5. A representative VCP-like complex, named as VCP-B3 was studied with both static and time-resolved spectroscopies with the aim of obtaining a deeper understanding of excitation energy migration within the pigment array of the complex. Compared to other VCP representatives, the absorption spectrum of the VCP-B3 is strongly altered in the range of the chlorophyll a Qy band, and is substantially red-shifted with the longest wavelength absorption band at 707 nm at 77 K. VCP-B3 shows a moderate xanthophyll-to-chlorophyll a efficiency of excitation energy transfer in the 50-60% range, 20-30% lower from comparable VCP complexes from other organisms. Transient absorption studies accompanied by detailed data fitting and simulations support the idea that the xanthophylls that occupy the central part of the complex, complementary to luteins in the LHCII, are violaxanthins. Target analysis suggests that the primary route of xanthophyll-to-chlorophyll a energy transfer occurs via the xanthophyll S1 state.

Chasing Multiple Bonding Interactions between Alkaline-Earth Metals and Main-Group Fragments.

Formally dianionic ligands such as alkylidenes or organoimidos play a major role in the organometallic chemistry of transition metals and are an emerging topical area of f-element chemistry. The pursuit and development of main-group-metal congeners has been tackled sporadically but is clearly lacking behind. The pronounced ionic bonding in particular, prevailing in alkali and alkaline-earth (Ae) metal derivatives, proved cumbersome. Recent substantial progress in the respective field of divalent Ae chemistry has been triggered by the implementation of new synthesis strategies involving new AeII precursors and tailor-made ligands. The main emphasis of this Minireview will be on the synthesis and reactivity of well-defined Group 2 alkylidenes, organoimides, silylenes, and phosphandiides.

Human autoreactive T cells recognize CD1b and phospholipids.

In contrast with the common detection of T cells that recognize MHC, CD1a, CD1c, or CD1d proteins, CD1b autoreactive T cells have been difficult to isolate in humans. Here we report the development of polyvalent complexes of CD1b proteins and carbohydrate backbones (dextramers) and their use in identifying CD1b autoreactive T cells from human donors. Activation is mediated by αß T-cell receptors (TCRs) binding to CD1b-phospholipid complexes, which is sufficient to activate autoreactive responses to CD1b-expressing cells. Using mass spectrometry and T-cell responses to scan through the major classes of phospholipids, we identified phosphatidylglycerol (PG) as the immunodominant lipid antigen. T cells did not discriminate the chemical differences that distinguish mammalian PG from bacterial PG. Whereas most models of T-cell recognition emphasize TCR discrimination of differing self and foreign structures, CD1b autoreactive T cells recognize lipids with dual self and foreign origin. PG is rare in the cellular membranes that carry CD1b proteins. However, bacteria and mitochondria are rich in PG, so these data point to a more general mechanism of immune detection of infection- or stress-associated lipids.

The fascial connections of the pectineal ligament.

In clinical settings, the pectineal ligament forms a basic landmark for surgical approaches. However, to date, the detailed fascial topography of this ligament is not well understood. The aim of this study was to describe the morphology of the pectineal ligament including its fascial connections to surrounding structures. The spatial-topographical relations of 10 fresh and embalmed specimens were dissected, stained, slice plastinated, and analyzed macroscopically, and in three cases histological approaches were also used. The pectineal ligament is attached ventrally and superiorly to the pectineus muscle, connected to the inguinal ligament by the lacunar ligament and to the tendinous origin of rectus abdominis muscle and the iliopubic tract. It forms a site of origin for the internal obturator muscle, and throughout its curved course, the ligament attaches to both the fasciae of iliopsoas and the internal obturator muscle. However, dorsally, these fasciae pass free from the bone, while the pectineal ligament itself is adhered to it. The organ fasciae are seen apart from the pectineal ligament and its connections. The pectineal ligament seems to form a connective tissue junction between the anterior and medial compartment of the thigh. This ligament, however, is free to other compartments arisen from the embryonal gut and to the urogenital ridge. These features of the pectineal ligament are important to consider during orthopedic and trauma surgical approaches, in gynecology, hernia and incontinence surgery, and in operations for pelvic floor and neovaginal reconstructions. Clin. Anat. 32:961-969, 2019. © 2019 Wiley Periodicals, Inc.

Vulvar field resection based on ontogenetic cancer field theory for surgical treatment of vulvar carcinoma: a single-centre, single-group, prospective trial.

BACKGROUND: The incidence of vulvar cancer is increasing, but surgical treatment-the current standard of care-often leads to unsatisfactory outcomes, especially in patients with node-positive disease. Preliminary results at our centre showed that locoregional spread of vulvar carcinoma occurs within tissue domains defined by stepwise embryonic and fetal development (ontogenetic cancer fields and associated lymph node regions). We propose that clinical translation of these insights into practice could improve outcomes of surgical treatment of vulvar cancer. METHODS: We did a single-centre prospective trial at the University of Leipzig's Cancer Center. Eligible patients were aged 18 years or older, had ontogenetic stage 1-3b histologically proven primary carcinoma of the vulva, and had not undergone previous surgical or radiotherapy treatment for vulvar cancer or any other major perineal or pelvic disease. In view of staged morphogenesis of the vulva from the cloacal membrane endoderm at Carnegie stage 11 to adulthood, we defined the tissue domains of tumour spread according to the theory of ontogenetic cancer fields. On the basis of ontogenetic staging, patients were treated locally with partial, total, or extended vulvar field resection; regionally with therapeutic inguinopelvic lymph node dissection; and anatomical reconstruction without adjuvant radiotherapy. The primary endpoints were recurrence-free survival, disease-specific survival, and early postoperative complications. Analysis of tumour spread and early postoperative surgical complications was done by intention to treat (ie, all patients were included), whereas outcome analyses were done per protocol. This ongoing trial is registered with the German Clinical Trials Register, number DRKS00013358. FINDINGS: Between March 1, 2009, and June 8, 2017, 97 consecutive patients were included in the study, of whom 94 were treated per protocol with vulvar field resection, therapeutic inguinopelvic lymph node dissection, and anatomical reconstruction without adjuvant radiotherapy. 46 patients had moderate or severe postoperative complications, especially infectious perineal and inguinal wound dehiscence. 3-year recurrence-free survival in all patients was 85·1% (95% CI 76·9-93·3), and 3-year disease-specific survival was 86·0% (78·2-93·8). INTERPRETATION: Our results support the theory of ontogenetic cancer fields for vulvar carcinoma, accord with our previous findings in cervical cancer, and suggest the general applicability of the theory. Application of the concept of cancer field resection could improve outcomes in patients with vulvar carcinoma, but needs to be investigated further in multicentre randomised controlled trials. FUNDING: Leipzig School of Radical Pelvic Surgery and Gynecologic Oncology Research Foundation.

Dimethylcalcium.

The salt metathesis reaction between homoleptic calcium bis(trimethylsilyl)amide [Ca{N(SiMe3)2}2]2 and "halide-free" methyllithium allowed for the isolation of X-ray-amorphous dimethylcalcium [CaMe2]n in good yields and purities. The formation of [CaMe2]n was proven by microanalysis and NMR/FTIR spectroscopic methods as well as a series of derivatization reactions. Despite slowly decomposing thf, [CaMe2]n could be crystallized from chilled thf solutions as the heptametallic adduct [(thf)10Ca7Me14]. Reaction of [CaMe2]n with CaI2 in thf led to the dimeric complex [(thf)3Ca(Me)(I)]2, whereas in tetrahydropyran (thp) the trinuclear complex [(thp)5Ca3(Me)5(I)] was obtained, both representing the first crystallographically characterized heavy-Grignard compounds with methyl groups as the hydrocarbyl ligand. While protonolysis of [CaMe2]n with the superbulky proligand HTptBu,Me in nonpolar solvents gave homoleptic (TptBu,Me)2Ca, reaction in donor solvents (thf, thp) afforded the monomeric complexes [(TptBu,Me)Ca(Me)(thf)] and [(TptBu,Me)Ca(Me)(thp)], which are the first examples bearing terminal Ca-CH3 functionalities. Grignard-type nucleophilic methyl-group transfer to hexamethylacetone gave access to the dimeric alkoxide complexes [(thf)Ca(OCtBu2Me)2]2 and [(tBu2CO)Ca(µ2-OCtBu2Me)3Ca(OCtBu2Me)]. Finally, addition of the Lewis acid GaMe3 to [CaMe2]n led to the corresponding tetramethylgallate compound [Ca(GaMe4)2]n.

Photoactivation and relaxation studies on the cyanobacterial orange carotenoid protein in the presence of copper ion.

Photosynthesis starts with absorption of light energy by light-harvesting antenna complexes with subsequent production of energy-rich organic compounds. However, all photosynthetic organisms face the challenge of excess photochemical conversion capacity. In cyanobacteria, non-photochemical quenching (NPQ) performed by the orange carotenoid protein (OCP) is one of the most important mechanisms to regulate the light energy captured by light-harvesting antennas. This regulation permits the cell to meet its cellular energy requirements and at the same time protects the photosynthetic apparatus under fluctuating light conditions. Several reports have revealed that thermal dissipation increases under excess copper in plants. To explore the effects and mechanisms of copper on cyanobacteria NPQ, photoactivation and relaxation of OCP in the presence of copper were examined in this communication. When OCPo (OCP at orange state) is converted into OCPr(OCP at red state), copper ion has no effect on the photoactivation kinetics. Relaxation of OCPr to OCPo, however, is largely delayed-almost completely blocked, in the presence of copper. Even the addition of the fluorescence recovery protein (FRP) cannot activate the relaxation process. Native polyacrylamide gel electrophoresis (PAGE) analysis result indicates the heterogeneous population of Cu2+-locked OCPr. The Cu2+-OCP binding constant was estimated using a hyperbolic binding curve. Functional roles of copper-binding OCP in vivo are discussed.

Characterization of a newly isolated freshwater Eustigmatophyte alga capable of utilizing far-red light as its sole light source.

Oxygenic phototrophs typically utilize visible light (400-700 nm) to drive photosynthesis. However, a large fraction of the energy in sunlight is contained in the far-red region, which encompasses light beyond 700 nm. In nature, certain niche environments contain high levels of this far-red light due to filtering by other phototrophs, and in these environments, organisms with photosynthetic antenna systems adapted to absorbing far-red light are able to thrive. We used selective far-red light conditions to isolate such organisms in environmental samples. One cultured organism, the Eustigmatophyte alga Forest Park Isolate 5 (FP5), is able to absorb far-red light using a chlorophyll (Chl) a-containing antenna complex, and is able to grow under solely far-red light. Here we characterize the antenna system from this organism, which is able to shift the absorption of Chl a to >705 nm.

Trade-offs between soil carbon sequestration and reactive nitrogen losses under straw return in global agroecosystems.

It is widely recommended that crop straw be returned to croplands to maintain or increase soil carbon (C) storage in arable soils. However, because C and nitrogen (N) biogeochemical cycles are closely coupled, straw return may also affect soil reactive N (Nr) losses, but these effects remain uncertain, especially in terms of the interactions between soil C sequestration and Nr losses under straw addition. Here, we conducted a global meta-analysis using 363 publications to assess the overall effects of straw return on soil Nr losses, C sequestration and crop productivity in agroecosystems. Our results show that on average, compared to mineral N fertilization, straw return with same amount of mineral N fertilizer significantly increased soil organic C (SOC) content (14.9%), crop yield (5.1%), and crop N uptake (10.9%). Moreover, Nr losses in the form of nitrous oxide (N2 O) emissions from rice paddies (17.3%), N leaching (8.7%), and runoff (25.6%) were significantly reduced, mainly due to enhanced microbial N immobilization. However, N2 O emissions from upland fields (21.5%) and ammonia (NH3 ) emissions (17.0%) significantly increased following straw return, mainly due to the stimulation of nitrification/denitrification and soil urease activity. The increase in NH3 and N2 O emissions was significantly and negatively correlated with straw C/N ratio and soil clay content. Regarding the interactions between C sequestration and Nr losses, the increase in SOC content following straw return was significantly and positively correlated with the decrease in N leaching and runoff. However, at a global scale, straw return increased net Nr losses from both rice and upland fields due to a greater stimulation of NH3 emissions than the reduction in N leaching and runoff. The trade-offs between increased net Nr losses and soil C sequestration highlight the importance of reasonably managing straw return to soils to limit NH3 emissions without decreasing associated C sequestration potential.

Lewis-Acid Stabilized Organoimide Complexes of Divalent Samarium, Europium, and Ytterbium.

Discrete organoimide complexes of the divalent rare-earth metals samarium, europium, and ytterbium are reported. Tandem salt metathesis-protonolysis reactions using LnII bis(tetramethylaluminate) precursors [Ln(AlMe4 )2 ]n and monopotassium salts of 2,6-diisopropylaniline (H2 NDipp) and triphenylsilylamine prove viable and efficient protocols. Depending on the ionic radius of the LnII metal centers and the steric demand of the imido carbon backbone, mono- and dilanthanide arrangements of general composition [(thf)x Ln(NR)(AlMe3 )]y (Ln=Sm, Eu, Yb; R=Dipp, SiPh3 ) are found in the solid state. Complex formation and stabilization is achieved by coordination of the Lewis acid AlMe3 , which also prevents formation of higher aggregated species. The feasibility of redox chemistry is shown with the plumbocene derivative Cp*2 Pb, providing access to the corresponding monomeric LnIII half-sandwich complexes [Cp*Ln(NR)(AlMe3 )(thf)2 ] (Ln=Sm, Yb).