Binding Analysis of Functionalized Multimode Optical-Fiber Sandwich-like Structure with Organic Polymer and Its Sensing Application for Humidity and Breath Monitoring.

In recent years, the chemical modification of optical fibers (OFs) has facilitated the manufacture of sensors because OFs can identify several analytes present in aqueous solutions or gas phases. Nevertheless, it is imperative better to understand the chemical interactions in this molecular system to generate low-cost and efficient sensors. This work presents a theoretical and experimental study of organic polymeric functionalized OF structures and proposes a cost-effective alternative to monitor breathing and humidity. The device is based on silicon optical fibers functionalized with (3-Aminopropyl) triethoxysilane (APTES) and alginate. The theoretical analysis is carried out to validate the activation of the silicon dioxide fiber surface; moreover, the APTES-alginate layer is discussed. The computational simulation suggests that water can be absorbed by alginate, specifically by the calcium atom linked to the carboxylic acid group of the alginate. The analysis also demonstrates a higher electrostatic interaction between the water and the OF-APTES-alginate system; this interaction alters the optical fiber activated surface's refractive index, resulting in transmission power variation. The humidity analysis shows a sensitivity of 3.1288 mV/RH, a time response close to 25 s, and a recovery time around 8 s. These results were achieved in the range of 50 to 95% RH. Moreover, the recovery and response time allow the human breath to be studied. The proposed mechanism or device is competitive with prior works, and the components involved made this sensor a cost-effective alternative for medical applications.

Redundant and Non-redundant Functions of the AHK Cytokinin Receptors During Gynoecium Development.

The phytohormone cytokinin is crucial for plant growth and development. The site of action of cytokinin in the plant is dependent on the expression of the cytokinin receptors. In Arabidopsis, there are three cytokinin receptors that present some overlap in expression pattern. Functional studies demonstrated that the receptors play highly redundant roles but also have specialized functions. Here, we focus on gynoecium development, which is the female reproductive part of the plant. Cytokinin signaling has been demonstrated to be important for reproductive development, positively affecting seed yield and fruit production. Most of these developmental processes are regulated by cytokinin during early gynoecium development. While some information is available, there is a gap in knowledge on cytokinin function and especially on the cytokinin receptors during early gynoecium development. Therefore, we studied the expression patterns and the role of the cytokinin receptors during gynoecium development. We found that the three receptors are expressed in the gynoecium and that they have redundant and specialized functions.

Enhanced Photocatalytic Activity of TiO2 Modified with GaI toward Environmental Application.

Gallium (Ga) ion-doped TiO2 (Ga-TiO2) nanocomposite with small particle size (9-10 nm) and high surface area (104 m2/g) has been easily synthesized via sol-gel method at low temperature by using low-valent GaI as a doping precursor. The structural and morphological characterization of Ga-TiO2 was carried out with standard analytical and spectroscopic techniques. Ga doping into the TiO2 matrix inhibited a phase transformation from anatase to rutile (photocatalytically inactive) form, even at a higher temperature of 750 °C. Finally, Ga-TiO2 nanocomposite showed high photocatalytic activity and exhibited 97% degradation of acid violet 63 dye within 60 min. The dye degradation rate constant was calculated as 1.6 × 10-1 and 1.4 × 10-1 min-1 under UV and white light irradiation, respectively, which is higher, as compared to the previously reported Ga-TiO2 composites to date.

New roles of NO TRANSMITTING TRACT and SEEDSTICK during medial domain development in Arabidopsis fruits.

The gynoecium, the female reproductive part of the flower, is key for plant sexual reproduction. During its development, inner tissues such as the septum and the transmitting tract tissue, important for pollen germination and guidance, are formed. In Arabidopsis, several transcription factors are known to be involved in the development of these tissues. One of them is NO TRANSMITTING TRACT (NTT), essential for transmitting tract formation. We found that the NTT protein can interact with several gynoecium-related transcription factors, including several MADS-box proteins, such as SEEDSTICK (STK), known to specify ovule identity. Evidence suggests that NTT and STK control enzyme and transporter-encoding genes involved in cell wall polysaccharide and lipid distribution in gynoecial medial domain cells. The results indicate that the simultaneous loss of NTT and STK activity affects polysaccharide and lipid deposition and septum fusion, and delays entry of septum cells to their normal degradation program. Furthermore, we identified KAWAK, a direct target of NTT and STK, which is required for the correct formation of fruits in Arabidopsis These findings position NTT and STK as important factors in determining reproductive competence.

Expression of ChiA74∆sp and its truncated versions in Bacillus thuringiensis HD1 using a vegetative promoter maintains the integrity and toxicity of native Cry1A toxins.

Our objective was to determine whether a recombinant chitinase ChiA74∆sp of Bacillus thuringiensis and its truncated versions (ChiA74∆sp-60, ChiA74∆sp-50) could be produced in B. thuringiensis HD1 with no detrimental effect on the size and insecticidal activity of the native bipyramidal Cry crystal. chiA-p, the promoter used to drive chitinase gene expression, was active during vegetative growth of Cry-B. HD1 recombinants showed increases from ~7- to 12-fold in chitinase activity when compared with parental HD1 and negligible or no effect on the volume of bipyramidal crystals was observed. HD1/ChiA74∆sp-60 showed increases from 20% to 40% in the yield of Cry1A per unit of culture medium when compared with parental HD1 and HD1/ChiA74∆sp-50, HD1/ChiA74∆sp. Inclusion bodies presumably composed of the enzyme attached to native Cry1A crystals of recombinant strains were observed; these inclusions were likely responsible for the enhancements in chitinase activity. Western blot analysis using polyclonal anti-ChiA74∆sp showed a weak signal with proteins of ~50 kDa in sporulated and lysed cells of recombinant strains. Bioassays against Spodoptera frugiperda using sporulated/lysed samples of the recombinant strains did not show statistically significant differences in LC50s when compared with HD1.

The bHLH transcription factor SPATULA enables cytokinin signaling, and both activate auxin biosynthesis and transport genes at the medial domain of the gynoecium.

Fruits and seeds are the major food source on earth. Both derive from the gynoecium and, therefore, it is crucial to understand the mechanisms that guide the development of this organ of angiosperm species. In Arabidopsis, the gynoecium is composed of two congenitally fused carpels, where two domains: medial and lateral, can be distinguished. The medial domain includes the carpel margin meristem (CMM) that is key for the production of the internal tissues involved in fertilization, such as septum, ovules, and transmitting tract. Interestingly, the medial domain shows a high cytokinin signaling output, in contrast to the lateral domain, where it is hardly detected. While it is known that cytokinin provides meristematic properties, understanding on the mechanisms that underlie the cytokinin signaling pattern in the young gynoecium is lacking. Moreover, in other tissues, the cytokinin pathway is often connected to the auxin pathway, but we also lack knowledge about these connections in the young gynoecium. Our results reveal that cytokinin signaling, that can provide meristematic properties required for CMM activity and growth, is enabled by the transcription factor SPATULA (SPT) in the medial domain. Meanwhile, cytokinin signaling is confined to the medial domain by the cytokinin response repressor ARABIDOPSIS HISTIDINE PHOSPHOTRANSFERASE 6 (AHP6), and perhaps by ARR16 (a type-A ARR) as well, both present in the lateral domains (presumptive valves) of the developing gynoecia. Moreover, SPT and cytokinin, probably together, promote the expression of the auxin biosynthetic gene TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS 1 (TAA1) and the gene encoding the auxin efflux transporter PIN-FORMED 3 (PIN3), likely creating auxin drainage important for gynoecium growth. This study provides novel insights in the spatiotemporal determination of the cytokinin signaling pattern and its connection to the auxin pathway in the young gynoecium.

Altered expression of the bZIP transcription factor DRINK ME affects growth and reproductive development in Arabidopsis thaliana.

Here we describe an uncharacterized gene that negatively influences Arabidopsis growth and reproductive development. DRINK ME (DKM; bZIP30) is a member of the bZIP transcription factor family, and is expressed in meristematic tissues such as the inflorescence meristem (IM), floral meristem (FM), and carpel margin meristem (CMM). Altered DKM expression affects meristematic tissues and reproductive organ development, including the gynoecium, which is the female reproductive structure and is determinant for fertility and sexual reproduction. A microarray analysis indicates that DKM overexpression affects the expression of cell cycle, cell wall, organ initiation, cell elongation, hormone homeostasis, and meristem activity genes. Furthermore, DKM can interact in yeast and in planta with proteins involved in shoot apical meristem maintenance such as WUSCHEL, KNAT1/BP, KNAT2 and JAIBA, and with proteins involved in medial tissue development in the gynoecium such as HECATE, BELL1 and NGATHA1. Taken together, our results highlight the relevance of DKM as a negative modulator of Arabidopsis growth and reproductive development.

Arabidopsis thaliana gonidialess A/Zuotin related factors (GlsA/ZRF) are essential for maintenance of meristem integrity.

Observation of a differential expression pattern, including strong expression in meristematic tissue of an Agave tequilana GlsA/ZRF ortholog suggested an important role for this gene during bulbil formation and developmental changes in this species. In order to better understand this role, the two GlsA/ZFR orthologs present in the genome of Arabidopsis thaliana were functionally characterized by analyzing expression patterns, double mutant phenotypes, promoter-GUS fusions and expression of hormone related or meristem marker genes. Patterns of expression for A. thaliana show that GlsA/ZFR genes are strongly expressed in SAMs and RAMs in mature plants and developing embryos and double mutants showed multiple changes in morphology related to both SAM and RAM tissues. Typical double mutants showed stunted growth of aerial and root tissue, formation of multiple ectopic meristems and effects on cotyledons, leaves and flowers. The KNOX genes STM and BP were overexpressed in double mutants whereas CLV3, WUSCHEL and AS1 were repressed and lack of AtGlsA expression was also associated with changes in localization of auxin and cytokinin. These results suggest that GlsA/ZFR is an essential component of the machinery that maintains the integrity of SAM and RAM tissue and underline the potential to identify new genes or gene functions based on observations in non-model plants.

The NTT transcription factor promotes replum development in Arabidopsis fruits.

Fruits are complex plant structures that nurture seeds and facilitate their dispersal. The Arabidopsis fruit is termed silique. It develops from the gynoecium, which has a stigma, a style, an ovary containing the ovules, and a gynophore. Externally, the ovary consists of two valves, and their margins lay adjacent to the replum, which is connected to the septum that internally divides the ovary. In this work we describe the role for the zinc-finger transcription factor NO TRANSMITTING TRACT (NTT) in replum development. NTT loss of function leads to reduced replum width and cell number, whereas increased expression promotes replum enlargement. NTT activates the homeobox gene BP, which, together with RPL, is important for replum development. In addition, the NTT protein is able to bind the BP promoter in yeast, and when this binding region is not present, NTT fails to activate BP in the replum. Furthermore, NTT interacts with itself and different proteins involved in fruit development: RPL, STM, FUL, SHP1 and SHP2 in yeast and in planta. Moreover, its genetic interactions provide further evidence about its biological relevance in replum development.

Hormones talking: does hormonal cross-talk shape the Arabidopsis gynoecium?

The proper development of fruits is important for the sexual reproduction and propagation of many plant species. The fruit of Arabidopsis derives from the fertilized gynoecium, which initiates at the center of the flower and obtains its final shape, size, and functional tissues through progressive stages of development. Hormones, specially auxins, play important roles in gynoecium and fruit patterning. Cytokinins, which act as counterparts to auxins in other plant tissues, have been studied more in the context of ovule formation and parthenocarpy. We recently studied the role of cytokinins in gynoecium and fruit patterning and found that they have more than one role during gynoecium and fruit patterning. We also compared the cytokinin response localization to the auxin response localization in these organs, and studied the effects of spraying cytokinins in young flowers of an auxin response line. In this addendum, we discuss further the implications of the observed results in the knowledge about the relationship between cytokinins and auxins at the gynoecium.

The role of cytokinin during Arabidopsis gynoecia and fruit morphogenesis and patterning.

Cytokinins have many essential roles in embryonic and post-embryonic growth and development, but their role in fruit morphogenesis is currently not really known. Moreover, information about the spatio-temporal localization pattern of cytokinin signaling in gynoecia and fruits is lacking. Therefore, the synthetic reporter line TCS::GFP was used to visualize cytokinin signaling during gynoecium and fruit development. Fluorescence was detected at medial regions of developing gynoecia, and, unexpectedly, at the valve margin in developing fruits, and was severely altered in mutants that lack or ectopically acquire valve margin identity. Comparison to developing gynoecia and fruits in a DR5rev::GFP line showed that the transcriptional responses to cytokinin and auxin are frequently present in complementary patterns. Moreover, cytokinin treatments in early gynoecia produced conspicuous changes, and treatment of valve margin mutant fruits restored this tissue. The results suggest that the phytohormone cytokinin is important in gynoecium and fruit patterning and morphogenesis, playing at least two roles: an early proliferation-inducing role at the medial tissues of the developing gynoecia, and a late role in fruit patterning and morphogenesis at the valve margin of developing fruits.