Differentiation of embryogenic pollen in cold-treated buds ofNicotiana tabacum var. Badischer burley and nutritional requirements of the isolated pollen to form embryos

Summary Embryogenic pollen were selectively isolated from buds after cold treatment at 10 °C for 10 days; it was immaterial whether the buds were taken from short day and low temperature (SD and LT; 8 hours light, 18 °C) or long day and high temperature (LD and HT; 16 hours light, 24 °C) plants. However, in buds from SD and LT plants the differentiation of embryogenic pollen could be detected as early as 7 days after the cold treatment, and pollen from these plants formed embryos at higher frequency (up to 4% of cultured pollen) than those from LD and HT plants (up to 1% only).The embryogenic pollen, in isolated buds, differentiated by way of pollen dimorphism. During cold treatment a fraction of pollen remained small, retained clear cytoplasm and was capable of embryogenesis in comparison to gametophytic pollen which enlarged and acquired granular cytoplasm. In our experiments cold treatment was a key factor in the induction of pollen dimorphism. This aspect of cold treatment in pollen embryogenesis is reported for the first time and was possible on the basis of selection of embryogenic pollen by density gradient centrifugation. The ratio of embryogenic pollen was about one fifth of the total population.The nutritional requirements of isolated pollen for embryogenesis were rather simple. These pollen formed embryos which readily developed into plantlets on a mineral medium supplemented with sucrose provided the pH was 6.8.     

Sodium chloride resistant cell line from haploidDatura innoxia mill

Summary A cell line resistant to sodium chloride was selected from callus cultures of haploidDatura innoxia by cloning under selective pressure. Cells of the resistant cell line retained their resistance even after subculture in absence of NaCl. Plantlets could be regenerated from resistant cells in the presence as well as absence of NaCl. In contrast, regeneration of plantlets was not possible from normal cells in the presence of NaCl, although regeneration readily occurred in the absence of NaCl.To examine the stability of the resistance in the long-term, callus cultures were initiated in presence of NaCl from stem expiants of the differentiated plantlets. All expiants of plantlets derived from resistant cells showed callus formation. This callus, derived from resistant explants, retained the trait of resistance upon subculture.     

Dark requirement for cell regeneration and colony formation by mesophyll protoplasts ofNicotiana plumbaginifolia Viv.

Summary The protoplasts ofNicotiana plumbaginifolia required darkness for cell regeneration and colony formation. Maximal plating efficiency of the protoplasts could be achieved by keeping the cultures in dark instead of light or dark/light sequence. Only two days of darkness prior to the illumination at 400 or 3,000 lux resulted in appreciable plating efficiency, than those of light from the beginning, but these values could not match the high plating efficiency in total darkness.     

T-rosettes in hemodialysis patients and renal allograft recipients

Subcellular fractions, isolated from the lymphoid cell line IM-1, are capable of stimulating a weak proliferative response in allogeneic lymphocytes. They also stimulate the generation of cytotoxic effector lymphocytes. The proliferative response to subcellular fractions, as measured by ³H-thymidine incorporation, is only one-fourth to one-sixth as great as that to intact IM-1 cells, suggesting that a component(s) synthesized during the mixed lymphocyte reaction (MLR), or a short-lived cellular constituent, may be responsible for the ability of intact cells to stimulate a lymphocyte proliferative response. This component appears to be lacking or in limiting quantity in subcellular fractions, including the soluble fractions. In contrast to the decreased proliferative response to subcellular fractions, the cytotoxic capacity of the stimulated lymphocytes is comparable to that after stimulation by intact IM-1 cells. The data demonstrate that, in this system, cytotoxic effector lymphocytes can be generated in the absence of the extensive proliferative response normally observed in the MLR. The antigenic stimulus responsible for the generation of cytotoxic effector cells appears to reside on intracellular components as well as on plasma membrane. In these reactions, specificity is shown by the failure of the cytotoxic cells to release ⁵¹Cr from autologous target cells. In fact, reactivity of lymphocytes stimulated by subcellular fractions is more specific than the reactivity of cells stimulated by intact IM-1 as judged by their lytic capacity for another target cell, RPMI 4265.     

Methods for Determining the Uncertainty of Population Estimates Derived from Satellite Imagery and Limited Survey Data: A Case Study of Bo City,Sierra Leone

This study demonstrates the use of bootstrap methods to estimate the total population of urban and periurban areas using satellite imagery and limited survey data. We conducted complete household surveys in 20 neighborhoods in the city of Bo, Sierra Leone, which collectively were home to 25,954 persons living in 1,979 residential structures. For five of those twenty sections, we quantized the rooftop areas of structures extracted from satellite images. We used bootstrap statistical methods to estimate the total population of the pooled sections, including the associated uncertainty intervals, as a function of sample size. Evaluations based either on rooftop area per person or on the mean number of occupants per residence both converged on the true population size. We demonstrate with this simulation that demographic surveys of a relatively small proportion of residences can provide a foundation for accurately estimating the total population in conjunction with aerial photographs.     

Isolation and characterization of catechol oxidase from Solanum melongena

Catechol oxidase was distributed in soluble and particulate fractions of Solanum melongena. The purified preparation appears to be homogeneous by polyacrylamide gel electrophoresis. The enzyme shows two pH maxima—with catechol, 6.5 and 7.5; and with dopa, 6.5 and 7.9. The latent form of the enzyme does not occur in S. melongena. The preparation resembles the enzyme from other sources in substrate specificity towards various mono- and diphenols, having a higher affinity for catechol than dopa; this tendency increases on purification. The cresolase activity decreases with purification and a lag period with p-cresol is observed. The oxidation of mono- and diphenols is inhibited by ascorbic acid, sulphydryl compounds and chelating agents.     

Lipid‐Embedded Molecular Dynamics Simulation Model for Exploring the Reverse Prostaglandin D2 Agonism of CT‐133 towards CRTH2 in the Treatment of Type‐2 Inflammation Dependent Diseases

Chemoattractant receptor‐homologous molecule expressed on Th2 cells (CRTH2) has been involved in several inflammation dependent diseases by mediating the chemotaxis of pro‐inflammatory cells in response to allergy and other responses through PGD2 ligation. This CRTH2‐PGD2 signaling pathway has become a target for treating allergic and type 2 inflammation dependent diseases, with many inhibitors developed to target the PGD2 binding pocket. One of such inhibitors is the ramatroban analog, CT‐133, which exhibited therapeutic potency cigarette smoke‐induced acute lung injury in patients. Nonetheless, the molecular mechanism and structural dynamics that accounts for its therapeutic prowess remain unclear. Employing computational tools, this study revealed that although the carboxylate moiety in CT‐133 and the native agonist PGD2 aided in their stability within the CRTH2 binding pocket, the tetrahydrocarbazole group of CT‐133 engaged in strong interactions with binding pocket residues which could have formed as the basis of the antagonistic advantage of CT‐133. Tetrahydrocarbazole group interactions also enhanced the relative stability CT‐133 within the binding pocket which consequently favored CT‐133 binding affinity. CT‐133 binding also induced an inactive or ‘desensitized’ state in the helix 8 of CRTH2 which could conversely favor the recruitment of arrestin. These revelations would aid in the speedy development of small molecule inhibitors of CRTH2 in the treatment of type 2 inflammation dependent diseases.     

Plant growth-promoting Bacillus sp. strain SDA-4 confers Cd tolerance by physio-biochemical improvements,better nutrient acquisition and diminished Cd uptake in Spinacia oleracea L.

Cadmium (Cd) is highly toxic metal for plant metabolic processes even in low concentration due to its longer half-life and non-biodegradable nature. The current study was designed to assess the bioremediation potential of a Cd-tolerant phytobeneficial bacterial strain Bacillus sp. SDA-4, isolated, characterized and identified from Chakera wastewater reservoir, Faisalabad, Pakistan, together with spinach (as a test plant) under different Cd regimes. Spinach plants were grown with and without Bacillus sp. SDA-4 inoculation in pots filled with 0, 5 or 10 mg kg⁻¹ CdCl₂-spiked soil. Without Bacillus sp. SDA-4 inoculation, spinach plants exhibited reduction in biomass accumulation, antioxidative enzymes and nutrient retention. However, plants inoculated with Bacillus sp. SDA-4 revealed significantly augmented growth, biomass accumulation and efficiency of antioxidative machinery with concomitant reduction in proline and MDA contents under Cd stress. Furthermore, application of Bacillus sp. SDA-4 assisted the Cd-stressed plants to sustain optimal levels of essential nutrients (N, P, K, Ca and Mg). It was inferred that the characterized Cd-tolerant PGPR strain, Bacillus sp. SDA-4 has a potential to reduce Cd uptake and lipid peroxidation which in turn maintained the optimum balance of nutrients and augmented the growth of Cd-stressed spinach. Analysis of bioconcentration factor (BCF) and translocation factor (TF) revealed that Bacillus sp. SDA-4 inoculation with spinach sequestered Cd in rhizospheric zone. Research outcomes are important for understanding morpho-physio-biochemical attributes of spinach-Bacillus sp. SDA-4 synergy which might provide efficient strategies to decrease Cd retention in edible plants and/or bioremediation of Cd polluted soil colloids.