A structured model for Thiobacillus ferrooxidans growth on ferrous iron

A structured model for Thiobacillus ferrooxidans growth dependence on ferrous and ferric iron, arsenic, oxygen, carbon dioxide, pH, and temperature is presented. A new kinetic mechanism for ferrous oxidation by T. ferrooxidans is introduced. Data from several earlier experimental studies of T. ferroaxidans growth are used for model development. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 310-319, 1997.     

The promising effects of BMP2 transfected mesenchymal stem cells on human osteosarcoma

Selective targeting of transfected mesenchymal stem cells (MSCs) carrying specific antioncogenes to the tumor was suggested as a treatment option. Bone morphogenetic protein-2 (BMP2) was shown to inhibit the proliferation and aggressiveness of osteosarcoma (OS) cells. Here, we aimed to assess the homing efficiency of intraperitoneally administered hMSCs transfected with BMP2 to the tumoral site and their effects on OS using an orthotopic xenograft murine model. Orthotopic xenograft murine model of OS in six-week-old female NOD/SCID mice using 143B cells was established. hMSCs transfected with BMP2 (BMP2⁺hMSC) were used. In vivo experiments performed on four groups of mice that received no treatment, or intraperitoneally administered BMP2, hMSCs, and BMP2⁺hMSCs. Histopathological and immunohistochemical studies were used to evaluate the pathological identification and to assess the dimensions and necrotic foci of the tumor, the features of lung metastases, and immunostaining against p27, Ki-67, and caspase-3 antibodies. The osteogenic differentiation markers BMP2, BMP4, COL1A1, OPN, OCN and PF4 evaluated using RT-PCR. The tumor dimensions in the hMSCs group were significantly higher than those of the remaining groups (p < 0.01). The number of metastatic foci in the BMP2⁺hMSCs group was significantly lower than those of the other groups (p < 0.01). The current results showed that the intraperitoneal route could be efficiently used for targeting hMSCs to the tumoral tissues for effective BMP2 delivery. In this study, the effects of BMP2 transfected hMSCs on human OS and metastasis were promising for achieving osteogenic differentiation and reduced metastatic process.     

Fungal Infections in COVID-19 Intensive Care Patients

Opportunistic fungal infections increase morbidity and mortality in COVID-19 patients monitored in intensive care units (ICU). As patients’ hospitalization days in the ICU and intubation period increase, opportunistic infections also increase, which prolongs hospital stay days and elevates costs. The study aimed to describe the profile of fungal infections and identify the risk factors associated with mortality in COVID-19 intensive care patients. The records of 627 patients hospitalized in ICU with the diagnosis of COVID-19 were investigated from electronic health records and hospitalization files. The demographic characteristics (age, gender), the number of ICU hospitalization days and mortality rates, APACHE II scores, accompanying diseases, antibiotic-steroid treatments taken during hospitalization, and microbiological results (blood, urine, tracheal aspirate samples) of the patients were recorded. Opportunistic fungal infection was detected in 32 patients (5.10%) of 627 patients monitored in ICU with a COVID-19 diagnosis. The average APACHE II score of the patients was 28 ± 6. While 25 of the patients (78.12%) died, seven (21.87%) were discharged from the ICU. Candida parapsilosis (43.7%) was the opportunistic fungal agent isolated from most blood samples taken from COVID-19 positive patients. The mortality rate of COVID-19 positive patients with candidemia was 80%. While two out of the three patients (66.6%) for whom fungi were grown from their tracheal aspirate died, one patient (33.3%) was transferred to the ward. Opportunistic fungal infections increase the mortality rate of COVID-19-positive patients. In addition to the risk factors that we cannot change, invasive procedures should be avoided, constant blood sugar regulation should be applied, and unnecessary antibiotics use should be avoided.     

Arabidopsis SMALL AUXIN UP RNA63 promotes hypocotyl and stamen filament elongation

Auxin regulates plant growth and development in part by activating gene expression. Arabidopsis thaliana SMALL AUXIN UP RNAs (SAURs) are a family of early auxin-responsive genes with unknown functionality. Here, we show that transgenic plant lines expressing artificial microRNA constructs (aMIR-SAUR-A or -B) that target a SAUR subfamily (SAUR61-SAUR68 and SAUR75) had slightly reduced hypocotyl and stamen filament elongation. In contrast, transgenic plants expressing SAUR63:GFP or SAUR63:GUS fusions had long hypocotyls, petals and stamen filaments, suggesting that these protein fusions caused a gain of function. SAUR63:GFP and SAUR63:GUS seedlings also accumulated a higher level of basipetally transported auxin in the hypocotyl than did wild-type seedlings, and had wavy hypocotyls and twisted inflorescence stems. Mutations in auxin efflux carriers could partially suppress some SAUR63:GUS phenotypes. In contrast, SAUR63:HA plants had wild-type elongation and auxin transport. SAUR63:GFP protein had a longer half-life than SAUR63:HA. Fluorescence imaging and microsomal fractionation studies revealed that SAUR63:GFP was localized mainly in the plasma membrane, whereas SAUR63:HA was present in both soluble and membrane fractions. Low light conditions increased SAUR63:HA protein turnover rate. These results indicate that membrane-associated Arabidopsis SAUR63 promotes auxin-stimulated organ elongation.     

An efficient micropropagation protocol for Citrus jambhiri Lush. and assessment of clonal fidelity employing anatomical studies and RAPD markers

Citrus jambhiri (rough lemon) is considered a major rootstock source for a number of Citrus species. A simple method for micropropagation from nodal segments is reported. Nodal segments of C. jambhiri were inoculated on MS medium supplemented with different concentrations and combinations of 6-benzylaminopurine (BAP), kinetin, and N6-(2-isopentenyl) adenosine (2iP). Maximum multiple shoot regeneration response (75?%) was observed with BAP at 3?mg?l^?1. Shoots were multiplied for 30?d on fresh medium with similar composition. A total of 67?% of the cultures showed multiplication with the optimum number of shoots (4.02) and height of shoots (1.81?cm) with BAP (3?mg?l^?1) alone. Maximum rooting response (87?%) was observed with naphthaleneacetic acid at 0.5?mg?l^?1. Transverse sections of shoot stems obtained in vivo (sampled from seedlings) and in vitro (regenerated from nodal segments), showed similar anatomies. Randomly amplified polymorphic DNA analysis confirmed that all the regenerated plants were genetically identical to their donor plant, suggesting absence of detectable genetic variation in the regenerated plantlets.     

In vitro response of encapsulated and non-encapsulated somatic embryos of Kinnow mandarin (Citrus nobilis Lour × C. deliciosa Tenora)

The aim of present investigation was to study the effect of storage conditions on percentage germination of encapsulated and non-encapsulated somatic embryos of Kinnow mandarin (Citrus nobilis Lour × C. deliciosa Tenora). Different batches of encapsulated and non-encapsulated embryos were preserved at room temperature, 4°C, in liquid nitrogen as such and by embedding in liquid paraffin. In the encapsulated somatic embryos stored at room temperature in sealed Petri plates, percentage of germination was 24.99%, but 5.55% in non-encapsulated embryos after 3 days of storage. Encapsulated embryos stored in vials containing liquid paraffin at room temperature were germinated at 18.05% after 60 days of storage, while it was 13.88% in non-encapsulated embryos after 45 days of storage. Encapsulated somatic embryos stored at 4°C in sealed Petri plates remained viable for up to 75 days with 6.94% germination, whereas non-encapsulated embryos remained viable for up to 45 days with 24.99% germination. Encapsulated embryos stored at 4°C in vials filled with paraffin germinated at 11.11% after 120 days of storage, but 5.55% in non-encapsulated embryos after 90 days of storage. Encapsulated and non-encapsulated embryos stored in liquid nitrogen showed 58.33 and 51.38% survival, respectively, after 7 months of storage. The plantlets developed from these embryos were transplanted after acclimatization and are growing normal.     

A new endemic species of Helichrysum Gaertn. (Asteraceae-Inuleae) from south Anatolia

A new species of Helichrysum Gaertn., H. orbicularifolium Sümbül, R. S. Göktürk & O. D. Düşen sp. nov. , is described and illustrated. The species is restricted to the south Anatolia Province, Antalya, Turkey, growing in humid calcareous rock crevices and on limestone cliffs. The species is compared with the closely related H. chasmolycicum . © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 141 , 251–254.     

Alterations in osteoclast morphology following osteoprotegerin administration in the magnesium-deficient mouse

In the present study, we used osteoprotegerin (OPG), which blocks osteoclastogenesis, to correct and thus explain the hypercalcemia that is seen during dietary Mg deficiency in the mouse. Control and Mg-deficient mice received injections for 12 days of either OPG or vehicle only. Serum Ca was similar in Mg-deficient mice treated with OPG and in control mice receiving OPG (9.2±0.3 mg/dl vs. 9.2±0.5). Both groups had significantly higher serum Ca than controls or Mg-deficient animals receiving vehicle alone. Surprisingly, Mg-depleted mice that received OPG in doses that inhibit osteoclastic bone resorption remained hypercalcemic. Because mature osteoclasts still present in the marrow might be hyperactive, we examined osteoclast morphology at the light microscopic and ultrastructural level. Light microscopic examination of trabecular bone showed few osteoclasts in OPG-treated mice. Ultrastructural examination revealed that osteoclasts in OPG-treated mice have decreased contact with the endosteal bone surface and absence of a ruffled border. Because the morphology of the existing pool of mature osteoclasts did not enhance resorption, another mechanism, such as increased intestinal absorption of Ca in Mg-deficient mice, likely contributes to the hypercalcemia observed during Mg deficiency.     

In vitro selection of resistant/tolerant mutants lines of Citrus jambhiri Lush. using crude culture filtrate of Phytophthora parasitica and their randomly amplified polymorphic DNA analysis

This study deals with in vitro‐induced mutagenesis and selection of Phytophthora tolerant lines of Citrus jambhiri and their regeneration. For in vitro‐induced mutagenesis, cotyledons were treated with ethyl methane sulfonate (EMS) 100, 200 and 300 mm for different time durations viz. 1, 3, 6 and 9 hr. Callus cultures were established from EMS treated cotyledon explants on MS medium supplemented with 2.0 mg/L of 2,4‐D and 500 mg/L of malt extract. Calli derived from cotyledon were challenged in vitro on selective MS medium containing 5%–100% of culture filtrate (CF) of the Phytophthora parasitica. Selected mutagen‐treated calli showed resistance in vitro on media containing CF. Calli treated with 100 mm EMS for 6‐hr duration showed tolerance (24%) up to 75% CF after 4th selection cycle. While, calli treated with 200 mm for 6‐hr duration showed maximum tolerance (76%) up to 75% CF. Resistant calli were then transferred to MS regeneration medium for shoot bud regeneration. A dose‐dependent decrease in the regeneration capacity of the selected calli was observed with the increasing concentration of the CF. In randomly amplified polymorphic DNA analysis, plantlets showed different banding pattern in comparison with the control plant, which confirms the presence of variations at genetic level.