Diurnal export and carbon economy in an expanding source leaf of cucumber at contrasting source and sink temperature

Effects of contrasting temperatures of an expanding leaf (source) and of remaining plant parts (sink) on diurnal export and distribution of carbon were studied in seedlings of Cucumis sativus L., cv. Farbio. The time course of the rate of export was calculated by measuring simultaneously the exchange of ¹⁴CO₂ and the amount of ¹⁴C in the source leaf by means of a Geiger-Müller detector using a steady-state labelling technique. In all treatments average export rate during the night (16 h) was maximally 50% of the average rate during the 8-h day. Temperature affected the diurnal course of export via the source leaf and the sink in different ways. At a source leaf temperature of 25 or 30°C export stopped 12 h after start of the night, whereas at 20°C export continued throughout the night. However, the total amount of carbon exported during a 24 h cycle, expressed as a proportion of the amount of carbon assimilated, was the same at source leaf temperatures of 20 or 30°C. Thus source leaf temperature did not affect the distribution of assimilates between source and sink, in contrast to sink temperature. After 24 h at a sink temperature of 30°C, 20% more ¹⁴C was exported to plant parts below the source leaf than with a sink temperature of 20°C, at the expense of carbon remaining in the source. During the day less starch and more structural dry matter was formed at a source leaf temperature of 30°C than at 20°C. After a complete day/night cycle, however, there was no difference between the treatments. Starch was the primary carbon source during the night, and the decline in the rate of export coincided with the depletion of starch. Thus the decline in the rate of export at a source leaf temperature of 25 or 30°C at 12 h after the start of the night was due to the depletion of starch at that time. Similarly, at 20°C export could continue until the end of the night as the starch degradation supplied assimilates during the whole night.     

Pathogenesis and Pathology of Invasive Aspergillosis

Purpose of Review

Invasive aspergillosis occurs in immunosuppressed individuals and is associated with high morbidity and mortality. Understanding the host defenses and pathogen characters is important in the causation of disease.

Recent Findings

Neutropenia and/or corticosteroid administration increase the risk of invasive infections and majority are due to Aspergillus fumigatus. The size of the conidia, thermotolerance, hydrophobins and melanin on conidial surface, adaptability to host environment, and angioinvasive nature contribute to pathogenecity. The large conidial size, hot and humid environment, and constant exposure to high spore content are implicated in the pathogenesis of chronic invasive infections in a normal host due to Aspergillus flavus. Pathology depends on the immune status and varies from granuloma with fibrosis or suppuration to abscess or infarction.

Summary

The risk factors and the interplay of host pathogen in the pathogenesis of invasive aspergillosis are reviewed. Genetic predisposition and identification of such genetic factors are necessary for prevention and treatment.

     

Mitigative effects of epigallocatechin gallate in terms of diminishing apoptosis and oxidative stress generated by the combination of lead and amyloid peptides in human neuronal cells

Environmental exposure to lead (Pb) is reported to associate with the development of Alzheimer's disease, where the formation of β‐amyloid peptides (APs) of (1‐40), (1‐42), and (25‐35) is considered as the major risk factor. In this context, we aimed at investigating the effect of epigallocatechin gallate (EGCG), a major flavonoid polyphenol available in green tea, in mitigating the individual and combined toxicity generated by Pb and β‐APs in terms of oxidative stress and apoptosis in human neuronal cells. SH‐SY5Y cells were exposed to Pb and β‐APs of (1‐40) and (25‐35) individually and in different combinations in the presence and absence of EGCG. The results indicated that EGCG mitigated both Pb‐ and β‐AP‐induced oxidative stress in scavenging reactive oxygen species and apoptosis by improving the expression levels of Bax and bcl2 and inhibiting annexin V and caspase‐3. Thus, our study shows that EGCG protects SH‐SY5Y cells against the cytotoxicity induced by Pb and β‐APs by decreasing oxidative stress and inhibiting apoptosis.     

Ionic derivatives of betulinic acid as novel HIV-1 protease inhibitors

Betulinic acid is a natural product possessing abundant and favourable biological activity, including anti-cancer, anti-malarial, anti-inflammatory and anti-HIV properties, while causing minimal toxicity to unaffected cells. The full biological potency of betulinic acid cannot be fully unlocked, however, for a number of reasons, a primary one being its limited solubility in aqueous and biologically pertinent organic media. Aiming to improve the water solubility of betulinic acid without disrupting its structurally related bioactivity, we have prepared different ionic derivatives of betulinic acid. Inhibition bioassays on HIV-1 protease-catalysed peptide hydrolysis indicate significantly improved performance resulting from converting the betulinic acid to organic salt form. Indeed, for one particular cholinium-based derivative, its water solubility is improved more than 100 times and the half maximal inhibitory concentration (IC(50)) value (22 μg mL(-1)) was one-third that of wide-type betulinic acid (60 μg mL(-1)). These encouraging results advise that additional studies of ionic betulinic acid derivatives as a therapeutic solution against HIV-1 infection are warranted.     

Role of vasorin,an anti‐apoptotic,anti‐TGF‐β and hypoxia‐induced glycoprotein in the trabecular meshwork cells and glaucoma

Glaucoma, one of the leading causes of irreversible blindness, is commonly associated with elevated intraocular pressure due to impaired aqueous humour (AH) drainage through the trabecular meshwork. The aetiological mechanisms contributing to impaired AH outflow, however, are poorly understood. Here, we identified the secreted form of vasorin, a transmembrane glycoprotein, as a common constituent of human AH by mass spectrometry and immunoblotting analysis. ELISA assay revealed a significant but marginal decrease in vasorin levels in the AH of primary open‐angle glaucoma patients compared to non‐glaucoma cataract patients. Human trabecular meshwork (HTM) cells were confirmed to express vasorin, which has been shown to possess anti‐apoptotic and anti‐TGF‐β activities. Treatment of HTM cells with vasorin induced actin stress fibres and focal adhesions and suppressed TGF‐β2‐induced SMAD2/3 activation in HTM cells. Additionally, cobalt chloride‐induced hypoxia stimulated a robust elevation in vasorin expression, and vasorin suppressed TNF‐α‐induced cell death in HTM cells. Taken together, these findings reveal the importance of vasorin in maintenance of cell survival, inhibition of TGF‐β induced biological responses in TM cells, and the decreasing trend in vasorin levels in the AH of glaucoma patients suggests a plausible role for vasorin in the pathobiology of ocular hypertension and glaucoma.     

Damage-induced chromatome dynamics link Ubiquitin ligase and proteasome recruitment to histone loss and efficient DNA repair

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Enhanced neogenic potential of Panc-1 cells supplemented with human umbilical cord blood serum--An alternative to FCS

The promise(s) of using Fetal Calf Serum (FCS) as a supplement for the maintenance of cell cultures has been well documented. However, FCS forms the xenogenic source for any human derived cells/organ and limits its application. Recently, the usage of human umbilical cord blood serum (hUCBS) for maintenance of mesenchymal cells has been supportive. In the present study we investigated the effects of hUCBS and FCS on the proliferation (viability, proliferative) and its differentiation potential (DTZ staining, immunofluroscence) to generate islet like cellular aggregates (ICAs) using the human derived Panc-1 cell lines. A comparative analysis of hUCBS and FCS for each parameter demonstrated that hUCBS supplemented media was better for proliferation and differentiation of the Panc-1 cells. The ICAs obtained from hUCBS primed cultures showed a higher yield, increased islet size, and showed an increase for insulin staining compared to FCS. We suggest that hUCBS can be explored as an alternate serum supplement for FCS, making it more feasible in cell systems of human derived origin and can also find its application for the human transplantation programmes.